Caroline Wozniacki

Despite being rivals, the two maintain a strong friendship off court. Wozniacki visited Williams during her recovery from injury in 2011. In 2014, it was announced that McIlroy had ended his engagement with Wozniacki just days prior to the French Open. Wozniacki received a call from her best friend Williams then in time of need. After they both lost early at the French Open, they went on vacation in Miami. They attended a Mariah Carey concert the night before their semifinal match at the WTA Finals. Williams was present during Wozniacki's run at the 2014 New York City Marathon. They also went on a mini tour around New York City. Wozniacki attended Williams' wedding in 2017. Williams served as a bridesmaid at Wozniacki's wedding in 2019. In 2018, Williams posted an Instagram story during US Open with the caption "Auntie Caro" as her daughter Olympia watches her match against Stosur. Wozniacki will play her last top level match in her career against Williams on May 18th, 2020 in Copenhagen.

On 6 December 2019, Wozniacki announced that she would retire from professional tennis following the 2020 Australian Open, held in January.

She won 30 WTA singles titles, including six in 2010 and 2011, the most in a year by a WTA player from 2008–2011. She was runner-up at the 2009 US Open and the 2010 WTA Tour Championships to Kim Clijsters, and at the 2014 US Open to Serena Williams. She won the 2006 Wimbledon girls' singles title and also holds two WTA titles in doubles. In 2008, Wozniacki won the title of WTA Newcomer of the Year. In 2017, she won the season-ending WTA Finals in Singapore for the first time in her career. Wozniacki won her maiden Grand Slam title at the 2018 Australian Open and returned to the No. 1 ranking on 29 January 2018.

At the Australian Open, Wozniacki was seeded second, her highest seeding since 2012. She defeated Mihaela Buzărnescu in straight sets and then beat Jana Fett in three sets after being down 1–5 in the third set and saving two match points. She then beat Kiki Bertens and Magdaléna Rybáriková both in straight sets to reach the quarterfinals, where she beat Carla Suárez Navarro in three sets to advance to her second Australian Open semifinal since 2011. In the semifinals, she beat Elise Mertens in straight sets to advance to her third Grand Slam final and her first since 2014. She then defeated top seed and world No. 1 Simona Halep in three sets, to become the ninth woman to win the title after being match point down. By winning her first Grand Slam title, she regained the world No. 1 ranking on 29 January 2018 after a gap of exactly six years, which bested Serena Williams' previous record of five years 29 days.

Wozniacki was scheduled to start her 2018 US Open Series in Washington, but withdrew due to a right leg injury. Instead, she played in the Canadian Open, where she received a bye in the first round. However, she lost to Aryna Sabalenka in three sets despite having three match points. One week later, in Cincinnati, she retired against Kiki Bertens in her first match of the tournament because of a left knee injury. In the US Open, Wozniacki defeated 2011 champion Samantha Stosur in straight sets, then lost to Lesia Tsurenko in the second round.

In October 2018, Wozniacki announced that she was diagnosed with rheumatoid arthritis, but would like to become a role model for people with the condition. She was diagnosed with the auto-immune disease before the 2018 US Open, but was able to play through it. Wozniacki did suffer a drop in results after her diagnosis, until bouncing back by winning the 2018 China Open in Beijing without dropping a single set.

Wozniacki was seeded 17th at the Australian Open. She reached the third round, defeating Arina Rodionova and Donna Vekic, but lost to Johanna Konta in straight sets.

Wozniacki competed in the Swedish Open and she made her fifth final of the year, beating Pauline Parmentier, Viktorija Golubic, Kateryna Kozlova and Elise Mertens before falling to Katerina Siniakova in the final. Wozniacki began her hard-court season in Rogers Cup in Toronto. Here she won her first ever match in Toronto defeating Ekaterina Alexandrova later in the quarterfinals she defeated the current world No. 1 for the first time, overcoming Karolina Plíšková in three sets. Wozniacki eventually made her sixth final of 2017 yet again falling at this stage, this time to Elina Svitolina. This tipped Wozniacki back into the top 5. She then competed in the Cincinnati Open defeating Elena Vesnina and Ashleigh Barty before falling in the quarterfinals to world No. 1 Karolina Plíšková. At the US Open, she defeated Mihaela Buzărnescu, then lost to Ekaterina Makarova in the second round.

On 14 February 2017, Valentine's Day, Wozniacki revealed on her social media accounts that she was in a relationship with former NBA champion David Lee, later being confirmed by her family. The couple got engaged on 2 November 2017. Wozniacki married Lee on 16 June 2019 in Tuscany. Serena Williams was one of her bridesmaids while Angelique Kerber, Agnieszka Radwańska and Urszula Radwańska were all among the guests. Also in attendance at the ceremony were Williams’ husband Alexis Ohanian, basketball players Pau Gasol and Harrison Barnes, and football player Jesse Palmer.

Wozniacki's next tournament was the e-Boks Sony Ericsson Open in her native Denmark. In the final, she defeated fourth seed Lucie Šafářová, taking her fifth title of the year. At Wimbledon, she had straight-set wins until the fourth round, but then lost to 24th seed Dominika Cibulková.

Wozniacki began her 2016 season at the ASB Classic in Auckland, where she was defending finalist points. She beat Danka Kovinić, Christina McHale, and Alexandra Dulgheru to advance to the semifinals where she lost to eventual champion Sloane Stephens in straight sets. Wozniacki's next tournament was the Australian Open where she lost to Yulia Putintseva in the first round in three sets, marking her worst performance at the tournament.

Wozniacki's next tournament was the St. Petersburg Ladies' Trophy. She lost to Dominika Cibulková in the second round in straight sets. Wozniacki next played the Qatar Open for which she needed nine match points to beat Ana Konjuh in the first round. She was at one point up by a double break in the third set. In the second round, she faced Daria Gavrilova which she won in straight sets. Wozniacki then played Elena Vesnina in the third round, she fell in a grueling match. Wozniacki played in the Monterrey Open instead of defending her title in Kuala Lumpur. She defeated Olga Govortsova in the first round and Mirjana Lucic-Baroni in the second round; however, she fell in the quarterfinals to the eventual winner Heather Watson. Caroline then played at the BNP Paribas Open and fell in the second round to Zhang Shuai. This match marked the longest match so far in 2016, at 3 hours and 24 minutes. Then in the Miami Open Wozniacki made a promising start, defeating Vania King; however, she fell to 12th seed Elina Svitolina.

Wozniacki began the year at the Auckland Open once again. This time, she was the No. 3 seed. She started out strong, breezing past Nicole Gibbs and Varvara Lepchenko, then lost in the quarterfinals to Julia Görges in three sets, despite being up a set and a break. At the Apia International Sydney, Wozniacki was seeded tenth. She played some solid tennis against Olympic gold medallist Monica Puig, winning in three sets. Wozniacki then defeated Yulia Putintseva in straight sets in a rematch of their 2016 Australian Open first-round clash. In the quarterfinals, she was defeated by Barbora Strycova in three close sets, despite twice being up a break in the final set.

In the Family Circle Cup, Wozniacki made it to the final, where she defeated unseeded Elena Vesnina to take her third title of the year, 15th of her career. In Stuttgart, she made it to her fifth final of the year, where she lost to Julia Görges in straight sets. In Madrid, Wozniacki lost to Görges again, this time in the third round. In Rome, she lost to eventual champion Maria Sharapova in the semifinal round. At the Brussels Open, Wozniacki reached the semifinals, where she defeated 3rd seed and reigning French Open champion, Francesca Schiavone. In the final, Wozniacki's sixth of the year, she defeated eighth seed Peng Shuai to win her first red clay title, having won three titles on the faster green clay. Wozniacki was the top seed at the French Open, but was upset in the third round by 28th seed Daniela Hantuchová.

Wozniacki moved on to the Toray Pan Pacific Open. In the first round, Wozniacki defeated Belinda Bencic, who had defeated her the previous year, in three sets. In the second round, she defeated fourth seed Carla Suarez Navarro, then beat qualifier Magda Linette in straight sets. In the semifinals, Wozniacki defeated defending champion Agnieszka Radwańska, which sent her off to her first final since April of the previous year. In the final, she defeated Japanese player Naomi Osaka to win her 24th WTA title, and her first title since March 2015. This was also Wozniacki's first Premier-level title since 2012.

Wozniacki dropped to No. 2 behind Clijsters during the week of 14 February, but regained the top spot the following week. She received a bye to the second round in Dubai where, in the quarterfinals, she beat Shahar Pe'er to ensure her No. 1 position in the next rankings update. She went on to defeat Svetlana Kuznetsova in the final to take her 13th career singles title and first of the year. In Doha, she received a bye to the second round and reached the final, defeating Nadia Petrova, Flavia Pennetta and Marion Bartoli in straight sets. She lost to Vera Zvonareva in the final. In the first Premier Mandatory event of the year in Indian Wells, Wozniacki made it to the final, where she defeated Marion Bartoli for her 14th singles title. At the Sony Ericsson Open in Miami, Wozniacki lost in the fourth round to 21st seed Andrea Petkovic. She made an uncharacteristic 52 unforced errors and later said she had been playing a lot of matches when she was asked about fatigue.

Her next tournament was the Toray Pan Pacific Open in Tokyo. She defeated Bojana Jovanovski, Daniela Hantuchová and Li Na, then lost to Agnieszka Radwańska in the quarterfinals. At the China Open in Beijing, Wozniacki defeated Chanelle Scheepers and Hsieh Su-wei but lost to Angelique Kerber in the third round. Wozniacki's next tournament was the Kremlin Cup. As the third seed in the tournament, she defeated top seed Samantha Stosur in the final in three sets to take home her second title of the year, and 20th overall. At the year-end Tournament of Champions in Sofia, Wozniacki won her three group matches and reached the final but lost to Nadia Petrova. She ended the year ranked 10th.

Wozniacki's first tournament of the 2014 US Open Series was Rogers Cup. She progressed to the quarterfinals with straight-set wins over Daniela Hantuchová, Klára Koukalová and Shelby Rogers, then lost to top seed Serena Williams. At the Western & Southern Open, she beat Magdaléna Rybáriková and Zhang Shuai, Angelique Kerber, and Agnieszka Radwańska. In the semifinals, she fell in three sets to the eventual champion Williams.

Wozniacki then decided to run the New York City Marathon in November 2014. She recorded a time of 3 hours, 26 minutes and 33 seconds. She claimed that the running training was positive for her and contributed to her good performances at the US Open and WTA Finals.

Wozniacki was in a relationship with Northern Irish professional golfer Rory McIlroy from 2011 until 2014. She announced their engagement via Twitter on 1 January 2014. On 21 May 2014, it was announced that McIlroy had ended the engagement: "The problem is mine. The wedding invitations issued at the weekend made me realise that I wasn't ready for all that marriage entails. I wish Caroline all the happiness she deserves and thank her for the great times we've had." Wozniacki later revealed that McIlroy had ended the relationship through a brief phone call, and had not contacted her since.

Wozniacki's father, Piotr, was her primary coach since she was 14. Throughout the years, she was coached by Sven Groeneveld through the Adidas Player Development Program. She was briefly coached by Ricardo Sanchez and Thomas Johansson. In October 2013, she hired Thomas Högstedt, but parted ways in January 2014. In the same month, she hired Michael Mortensen, but cut ties with him in March 2014. Since then, Wozniacki decided to be coached again by her father Piotr for the rest of her career.

Wozniacki's final win–loss record for the year (ITF matches included, exhibition matches not included) was 58–20 in singles and 8–9 in doubles. She ended the year ranked 12th in singles and 79th in doubles. She finished 13th in the race for the Sony Ericsson Championships. She won the Newcomer of the Year award for 2008.

On her 19th birthday, she lost the final of the Swedish Open to María José Martínez Sánchez. On hard court at the LA Women's Tennis Championships, she lost in the second round to Sorana Cîrstea. At the Cincinnati Masters, she reached the quarterfinals, then lost to Elena Dementieva. In Toronto, she lost early in the second round to Zheng Jie, but she then went on to defend her title at the Pilot Pen Tennis in New Haven without losing a set. In the first round, she had her first double bagel win as a professional, 6–0, 6–0, over Edina Gallovits in 41 minutes. In the final, she beat Elena Vesnina for her third title of the season.

In the second round of the Toray Pan Pacific Open, she retired because of a viral illness down 0–5 against Aleksandra Wozniak. She then lost to María José Martínez Sánchez in the first round of the China Open, and to Samantha Stosur in the semifinals in Osaka. The following week in Luxembourg, she retired with a hamstring injury in the first round while leading 7–5, 5–0 over Anne Kremer. This aroused controversy because of the scoreline.

Her next tournament was in Ponte Vedra Beach, where she defeated Olga Govortsova in the final. Wozniacki then competed at the Family Circle Cup in Charleston. She advanced to the semifinals, where she met Vera Zvonareva. Wozniacki was forced to retire down 2–5 when she rolled her ankle.

The Australian Open was Wozniacki's first major as world No. 1. She lost to Li Na in the semifinals, failing to convert a match point when trying to serve out the match at 5–4 in the second set.

At the Rogers Cup, Wozniacki made an early second-round exit. She was defeated by Roberta Vinci in straight sets despite holding a 5–1 lead in the second set. Wozniacki was the top seed at the Western & Southern Open in Cincinnati, but lost in the second round to world No. 76 Christina McHale. Next playing at the New Haven Open at Yale, Wozniacki won the title for the fourth year in a row, defeating Francesca Schiavone in the semifinals and qualifier Petra Cetkovská in the final.

At the US Open, Wozniacki was the first seed. In the first round, she defeated Nuria Llagostera Vives. In the second round, Wozniacki defeated Arantxa Rus, and in the third round, defeated Vania King. In the fourth round, Wozniacki fought back from a 7–6, 4–1 deficit, defeating Svetlana Kuznetsova. Wozniacki then progressed to the semifinals by defeating Andrea Petkovic in the quarterfinals. In the semifinals she lost to Serena Williams.

Wozniacki began her grass-court season at the Aegon International in Eastbourne. She reached the semifinals with victories over Tamira Paszek, Laura Robson and Ekaterina Makarova but then lost to qualifier Jamie Hampton. In the first round of Wimbledon, Wozniacki beat Estrella Cabeza Candela. In the second round, she faced Petra Cetkovská. In just the fourth game of the first set, with the score at 2–1 and going with serve, Wozniacki slipped and fell, injuring her ankle. She received treatment but was visibly struggling and went on to lose the match. Wozniacki was one of several players to slip and injure themselves, including Jo-Wilfried Tsonga, Victoria Azarenka and Maria Sharapova. After the match, Wozniacki questioned whether the preparation for the tournament was the same as in previous years, adding: "I just know that it's just not really fun to be out there when you feel like you can't really push off on your foot."

At the WTA Finals, Wozniacki was drawn into the White Group alongside Sharapova, Kvitová and Radwańska. In her first match she beat Maria Sharapova in three sets. She then went on to beat Agnieszka Radwańska in straight sets. With Sharapova winning in three sets against Radwańska, Wozniacki qualified into the semifinals. She then beat Kvitová in straight sets going undefeated in her round robin matches. She would lose to Serena Williams in the semifinals in three sets despite serving for the match in the third set and leading 4–1 in the third set tiebreak. She finished the year ranked at No. 8.

Wozniacki began her US hard-court season in Washington, playing the Citi Open she went on to beat Hiroko Kuwata in the first round and retired in her second-round clash with Sam Stosur despite being up a set 7–5 a sharp pain in her left arm forced her to retire. This injury also took her out of The Rogers Cup. She then played the Summer Olympic Games. Dropping four games, she beat Lucie Hradecka but fell to Czech Petra Kvitová in the second round. She failed to win a match in the Connecticut Open as she lost in the first round to young Latvian Jelena Ostapenko. However, Wozniacki's year turned around at the US Open. She slid past Taylor Townsend in three sets, then upset Svetlana Kuznetsova in round two. She then beat Monica Niculescu in two sets to reach the fourth round, in which she upended Madison Keys in two sets to reach the quarterfinals and then beat unseeded Anastasija Sevastova to enter the semifinals. Wozniacki lost the semifinal to then-new No. 1 Angelique Kerber, in two sets, and resulting at the back of the top 30 for the first time since April of this year.

At the BNP Paribas Open, Wozniacki beat Magda Linette, Kateřina Siniaková and Madison Keys, not losing a set, to advance to the quarterfinals where she lost to Kristina Mladenovic. At the Miami Open, Wozniacki beat Varvara Lepchenko and Sorana Cîrstea in straight sets and then advanced to the quarterfinals with a retirement from Garbiñe Muguruza. In the quarterfinals, she beat Lucie Šafářová in straight sets and in the semifinals, avenged her Doha loss to Karolína Plíšková by beating her in three sets to advance to her first ever final in Miami and her first Mandatory final since 2013. She lost in straight sets to Johanna Konta.

Wozniacki and Serena Williams have met 11 times with Williams leading the head to head 10–1. Williams leads 2–0 in Grand Slams, 8–1 on hard courts, and 1–0 on both clay and grass. Both held the No. 1 ranking from early November 2009 to late January 2012. They are currently the top 2 active players to hold the No. 1 ranking for the most weeks.

Wozniacki and Agnieszka Radwańska have met 17 times with Wozniacki leading the head to head 11–6. Wozniacki leads 9–6 on hard courts and 2–0 on clay.

Wozniacki and Maria Sharapova have met 11 times with Sharapova leading the head-to-head 7–4. Wozniacki leads 2–1 in Grand Slams with two wins at the US Open and one loss at the Australian Open. They are tied at 4–4 on hard courts, while Sharapova leads 3–0 on clay.

Wozniacki and Simona Halep have met seven times with Wozniacki leading the head to head 5–2. Wozniacki leads 3–2 on hard courts, 1–0 on both clay and grass courts and 1–0 in the Grand Slams.

The pair have met ten times in their career, with Wozniacki holding a 6–4 advantage over Pliskova, Wozniacki leads 6–3 on hard courts, Pliskova leading 1–0 on grass. They have never met at Grand Slam level.

The rivalry between Wozniacki and Karolina Pliskova didn't seem to brew very fast at the beginning of their meetings. The first three meetings occurred in 2013 and 2014 and all three meetings went the way of Wozniacki, all of which happening in three sets. Their rivalry really picked up in 2017 where the pair met six times, in this year their head to head record was 3–3 and each meeting would alternate the winner. The first meeting came in the final stage of 2017 Qatar Total Open, Pliskova winning is straight sets. A month later in the semifinals of 2017 Miami Open, Wozniacki took victory in three sets. Later, on the grass Pliskova took the 2017 Aegon International Eastbourne title beating Wozniacki in straight sets. Their fourth meeting was arguably the match of the year, in the 2017 Rogers Cup quarterfinals, where Wozniacki stormed back from 1–5 down in the first set and break down in the third set to take the victory. One week later, the pair met in the 2017 Western & Southern Open quarterfinals where Pliskova dispatched a tired Wozniacki from making the final of Toronto the previous week. At the semifinal stage of the 2017 WTA Finals, Wozniacki won a marathon first set propelling her to a straight sets victory over Pliskova, and eventually lifting the title. The last meeting in 2018 occurred at the round robin of the 2018 WTA Finals where Wozniacki was upset in straight sets.

Wozniacki began her season by representing Denmark at the 2012 Hopman Cup with Frederik Nielsen as her partner. Wozniacki won two of her three round robin matches in singles, defeating Bethanie Mattek-Sands and Tsvetana Pironkova, then lost to world No. 2 Petra Kvitová. Her first WTA event was the Apia International Sydney. Wozniacki defeated Dominika Cibulková when trailing 4–0 in the third set. She lost to Agnieszka Radwańska in three sets in the quarterfinals, after serving for the match at 5–4 up in the second set.

Wozniacki competed at the Australian Open as the top seed. She defeated Anastasia Rodionova, Anna Tatishvili, Monica Niculescu and Jelena Janković, all in straight sets, to reach the quarterfinals where she lost to the defending champion Kim Clijsters. As a result, Wozniacki lost her top ranking and was replaced by the 2012 champion Victoria Azarenka. Next playing at Doha, Wozniacki lost to Lucie Šafářová in the second round, having received a first-round bye. Wozniacki was the defending champion in Dubai and Indian Wells, but failed to defend either title, losing to Julia Görges and Ana Ivanovic, respectively.

In December 2012, during an exhibition match in Brazil, Wozniacki imitated friend and fellow tennis player Serena Williams by stuffing towels in her shirt and skirt in order to appear to be large-chested and have a large rear end. This act divided opinion on social network sites. It was noted that Wozniacki had done the impression before without controversy. Williams also defended Wozniacki in an email to USA Today and pointed out that they are friends and that the act was not racist. Williams added, however, that if people feel this way, then she should do something else next time.

Wozniacki's next tournament was the US Open, where she was the tenth seed. She faced Magdaléna Rybáriková in her opening match, progressing when her opponent was forced to retire early in the third set. She then beat qualifier Aliaksandra Sasnovich in the second round in straight sets. In the third round she easily took care of 18th seed Andrea Petkovic in straight sets for her first win over a seeded player at a grand slam since 2012. In the fourth round, Wozniacki came up against former world No. 1 and former champion Maria Sharapova, defeating her in three sets to progress to the quarterfinals of a grand slam for the first time since the 2012 Australian Open. In the quarterfinals, she dropped just one game to breeze past Sara Errani. In the semifinals, Wozniacki came up against unseeded Peng Shuai. Wozniacki was up a set when her opponent was forced to retire due to a severe heat-related illness, allowing Wozniacki to advance to her second Grand Slam final, and her first since the 2009 US Open. In the final, Wozniacki came up against two-time defending champion Serena Williams for the third time in four weeks, again falling to the world No. 1. Due to her run to the final, Wozniacki returned to the top 10 for the first time since February.

Wozniacki won her second title of the season and 25th title overall at the Hong Kong Open. She defeated Zheng Saisai, Heather Watson, Wang Qiang, Jelena Jankovic, add Kristina Mladenovic. This was the first time since 2012 that Wozniacki had won two WTA titles in a single season. With the win, Wozniacki returned to the top 20.

They first met at the 2012 Dubai Tennis Championships with Wozniacki winning in straight sets. Then, Halep won the next two matches, one at the 2013 New Haven Open at Yale in straight sets and another one at the 2015 Dubai Tennis Championships in three sets. Wozniacki then took a four-match winning streak over Halep, beginning at the 2015 Stuttgart Open and including their most recent meeting at the 2018 Australian Open in the final, where she defeated Halep in three sets to win her first Grand Slam title and snatch the world No. 1 position from Halep.

According to the June 2011 edition of SportsPro, Wozniacki is the world's ninth-most marketable athlete. According to Forbes in 2011, Wozniacki was the second-highest-earning female athlete in the world.

Wozniacki started the season in Auckland, where she lost to Elena Vesnina in the quarterfinals. She also reached the quarterfinals in Sydney, this time losing to world No. 2 Serena Williams after having three match points. Seeded 11th at the Australian Open, Wozniacki lost in the third round to Australian Jelena Dokic.

During the off season, Wozniacki switched her racquet make from Babolat to Yonex. She began her 2011 season with an exhibition match in Thailand against Kim Clijsters where she lost in a super tie-break. Wozniacki then played another exhibition, the team Hong Kong Tennis Classic, where she represented and was captain of Team Europe. She won two matches against Team Asia Pacific, then was crushed by world No. 2 Vera Zvonareva in the final against Team Russia. Her first WTA tournament was the Medibank International Sydney. She received a bye to the second round, where she lost to Dominika Cibulková.

In Tokyo, Wozniacki lost to Kaia Kanepi in the third round. In Beijing, she lost to Flavia Pennetta in the quarterfinals. This was Wozniacki's only loss in the 12 quarterfinals she reached in 2011.

Wozniacki started her clay season in Stuttgart where she was seeded fourth. In the second round, she beat Lucie Šafářová in straight sets. In the quarterfinals, she dropped just three games against Carla Suárez Navarro to advance to the semifinals. In the semifinals, she beat Simona Halep in a three-set thriller to reach her first clay court final since 2011. She lost to Angelique Kerber in the final in three sets, despite serving for the match in the third set. Wozniacki's next tournament was the Mutua Madrid Open where she made it to the quarterfinals for the first time since 2009 beating Jarmila Gajdošová, Christina McHale and Agnieszka Radwańska. She lost in the quarterfinals to Maria Sharapova in three sets. Wozniacki's next tournament was the Internazionali BNL d'Italia. She lost in the second round to Victoria Azarenka for the third time in straight sets. Wozniacki then played at the French Open as the fifth seed. She beat Karin Knapp in straight sets, then lost to Julia Görges in the second round in straight sets.

In 2009, Wozniacki signed on to become an endorser for the line of tennis apparel designed by Stella McCartney for Adidas. She wore her first 'Adidas by Stella McCartney' tennis dress at the 2009 US Open. She currently has partnership agreements with Babolat, Rolex, Adidas, USANA, The Players' Tribune and Mundipharma. On 20 December 2010, she signed a three-year deal to endorse Turkish Airlines' business class service. In 2012, Wozniacki became an endorser of Compeed BlisterPatch. At the end of 2013 she switched her racquet sponsorship from Yonex back to her long-time partner Babolat. In 2015, Wozniacki became an endorser of Godiva Chocolatier. In 2018 she entered into a partnership with Lympo, a healthy lifestyle motivation app.

Wozniacki suffered early exits in her next two tournaments, losing to Marion Bartoli in the second round in Stuttgart, and to Victoria Azarenka in the third round in Rome. She reached the final of the inaugural Premier Mandatory Mutua Madrileña Madrid Open, where she lost to world No. 1 Dinara Safina. This was Wozniacki's only match against a reigning No. 1 before she became No. 1 in October 2010. Seeded 10th at the French Open, Wozniacki lost to Sorana Cîrstea in the third round. They partnered in doubles, but lost in the first round.

Wozniacki was the top seed at the US Open due to the withdrawal of world No. 1 Serena Williams. She advanced to the semifinals, then lost to Vera Zvonareva. With her semifinal appearance, Wozniacki became one of only two women (the other being Venus Williams) to have reached at least the fourth round of all four Grand Slam events in 2010.

Wozniacki reached the semifinals in Miami, beating Barbora Záhlavová-Strýcová, Petra Cetkovská, Yanina Wickmayer and Serena Williams, all in straight sets. Wozniacki then lost to 2nd seed Maria Sharapova. Wozniacki did not defend her title in Charleston as she was not allowed to participate under WTA rules because two top-6 players had already entered the draw. Wozniacki then played her home tournament in Copenhagen. She reached the final but lost to Angelique Kerber, her first loss at the tournament since the start in 2010.

Her next tournament was the BNP Paribas Open where she was defending runner-up points. She reached the fourth round following wins over Bojana Jovanovski and Yaroslava Shvedova, then lost to Jelena Janković, causing her to fall to world No. 18, her lowest ranking since 2010. She recovered by reaching the quarterfinals of the Sony Open, recording wins over Monica Puig, Sloane Stephens and Varvara Lepchenko before losing to Li Na. Wozniacki made her debut at the Monterry Open, where she defeated CoCo Vandeweghe, Kristina Mladenovic and Karolína Plíšková en route to the semifinals, then lost to the eventual champion Ana Ivanovic.

Wozniacki began her clay court season at the Volvo Car Open. She made it to the quarterfinals with straight-set wins over Annika Beck and Anastasia Rodionova. There she lost to Jeļena Ostapenko in straight sets. She next played at the Prague Open, beat Misaki Doi in the first round in straight sets, and lost to Ostapenko again in three sets despite having match point. Wozniacki next played at the Madrid Open. In the first round, she beat Monica Niculescu in three sets, then lost to Carla Suárez Navarro in three sets. In Strasbourg, Wozniacki retired from her first match against Shelby Rogers. Wozniacki then played at the French Open as the 11th seed. She beat Jaimee Fourlis in the first round in three sets, then beat Françoise Abanda without the loss of a game. In the third round, she beat CiCi Bellis in three sets and then went on to beat former champion Svetlana Kuznetsova in three sets to advance to the quarterfinals for the first time since 2010. She lost to eventual champion Jeļena Ostapenko for the third time in three sets.

At the WTA Finals, Wozniacki beat Elina Svitolina for the first time after losing to her twice in finals. She then defeated the world No. 1, Simona Halep, in straight sets. In her third and final match of round robin play, she was defeated by Caroline Garcia in three sets. Nonetheless, she still made the semifinals. In the semifinals, she beat Karolina Pliskova in straight sets to advance to the final for the first time since 2010, where she finished runner-up. In the final, she beat Venus Williams for the first time to win the biggest title of her career. By virtue of her WTA Finals crown, she moved up to world No. 3 where she would finish the season, her highest year-end ranking since 2011.

Wozniacki won her second 2009 title on the grass of Eastbourne. In the final, she defeated Virginie Razzano. Wozniacki was seeded ninth at Wimbledon, where she lost to Sabine Lisicki in the fourth round.

Wozniacki's stellar 2009 results qualified her for the year-end Sony Ericsson Championships in Doha for the first time. She won two of three group matches and advanced to the semifinals. There she struggled with a stomach strain and a left thigh injury against world No. 1 Serena Williams, and retired while trailing 6–4, 0–1.

Wozniacki's woeful season continued at the Rogers Cup, where she fell in the second round to Sorana Cîrstea despite having double match point in the second set. She then reached the quarterfinals of the Western & Southern Open, beating Peng Shuai, Monica Niculescu and Petra Kvitová, but was defeated by Victoria Azarenka for the first time since 2009. Wozniacki then played at the New Haven Open at Yale. She reached the semifinals beating Peng via retirement, Karin Knapp and Sloane Stephens, then lost to Simona Halep in straight sets. At the US Open, Wozniacki defeated Duan Yingying and Chanelle Scheepers in straight sets, then lost to qualifier Camila Giorgi in the third round. This marked the first time since 2008 where Wozniacki had failed to reach the quarterfinals or better at one of the four Grand Slam tournaments.

They first met at the 2009 Medibank International Sydney with Williams winning in three tight sets saving match points. Wozniacki's only win over Williams came at the 2012 Sony Ericsson Open where she won in straight sets. In 2014 the rivalry reached its peak with the pair meeting four times and Williams winning all of them. Three of their four meetings went to three sets with Williams coming from a set down in each to win. At the Rogers Cup Wozniacki led by a set and a break before Williams came back to win it. They met a week later at the Western & Southern Open where Williams again came from a set down to win. They faced off against each other in the final at the US Open where Williams won in straight sets to claim her 18th Grand Slam title. Their most recent meeting at the WTA Finals was an epic with Wozniacki winning the first set before Williams came back to win the second set. At 4–4 Wozniacki broke Williams to serve for the match and Williams broke back. At 6–5 Wozniacki saved match point with an incredible volley and held serve to take the set to a tiebreak. In the tiebreak, Wozniacki was up 4–1 before Williams came back and eventually prevailed.

Wozniacki was scheduled to play many clay court tournaments, but she injured her ankle during a practice, which put her out for all of the clay-court season. This break saw Wozniacki fall through the rankings from 22 down to 34, the lowest since May 2008. She withdrew from the French Open because her ankle was not 100%.

Wozniacki played in Nottingham, her first tournament since the Miami Open in March and her first tournament after hiring her new coach David Kotyza. Wozniacki won her first match in 10 weeks defeating Çağla Büyükakçay, but falling in yet another three-set match to Anett Kontaveit in the second round. In her last tournament leading up to Wimbledon, Wozniacki played the Aegon International Eastbourne. She showed signs of improvement from her loss of form and injury, dismissing Alizé Cornet and 7th seed Sam Stosur and dropping only seven games in the two matches, then lost in a three-set match to qualifier Monica Puig. In Wimbledon, she went unseeded in the tournament, the first time since 2008 Australian Open, and lost to Svetlana Kuznetsova in the first round, resulting in her falling out of the top 50 for the first time since February 2008.

The pair first met at the 2008 Qatar Total Open where Sharapova won in straight sets and then again at the 2008 Rome Masters. Wozniacki then won the next two meetings to tie the head-to-head. Sharapova then won the next three meetings including their only meeting in a final at the 2013 BNP Paribas Open. Wozniacki snapped the losing streak by beating Sharapova in three sets at the 2014 US Open and would go on to the reach the final. They met again at the 2014 WTA Finals where Wozniacki won in three sets in a marathon match that lasted over three hours. Their most recent meeting was at the 2019 Australian Open where Sharapova won in three sets.

On 4 February 2007, she won a $75,000 singles title in Ortisei, beating Italian Alberta Brianti. On 4 March, she won the $75,000 tournament in Las Vegas, beating top-seed Akiko Morigami in the final. She obtained a wildcard for the Pacific Life Open main draw and made her Tier I debut there. She was knocked out in the second round by Martina Hingis. She then made the semifinals of the AIG Open in Tokyo in October, her first career WTA Tour semifinal, and as a result became the first Danish woman to reach a WTA semifinal since Tine Scheuer-Larsen at Bregenz in 1986. She was defeated by Venus Williams in straight sets.

She then played the French Open, where she lost to Kaia Kanepi in three sets in the third round. At the Wimbledon, she lost to Austrian Tamira Paszek in the first round. It was her first opening-round exit from any Grand Slam since making her professional debut at the 2007 French Open.

Wozniacki's next tournament was the Generali Ladies Linz. She beat Mirjana Lučić-Baroni in three sets, then lost to Kirsten Flipkens in the second round in straight sets. Wozniacki failed to qualify for the WTA Finals, but she did qualify for the Elite Trophy where she was drawn into Group D alongside Roberta Vinci and Svetlana Kuznetsova. After retiring in her first match against Svetlana Kuznetsova, Wozniacki withdrew from the tournament. She finished the year ranked at No. 17, her worst year-end ranking since 2007.

In Indian Wells, she lost to Ekaterina Alexandrova in three tight sets. In Miami, she made it to the fourth round by beating Aliaksandra Sasnovich and Monica Niculescu, but lost to Hsieh Su-wei in three sets. In April, she began her clay court season by making the final at the Charleston Open, but lost to Madison Keys in two tough sets. Wozniacki ended her season without winning a title for the first time since 2007. In December, Wozniacki announced that she was going to retire from tennis after the 2020 Australian Open where she won her first and only grand slam title.

They first met at the 2007 Nordea Nordic Light Open with Radwańska taking the victory in straight sets. After that win, Wozniacki won the next five matches before the streak snapped at the 2012 Apia International Sydney where she lost in three sets. Radwańska then won the next two matches before that streak was snapped at the 2014 Western & Southern Open where she lost in straight sets. After this event, Wozniacki took another four consecutive wins, then she lost at the 2016 Wuhan Open in straight sets. A week later, she lost again at the 2016 China Open in straight sets. Their next two meetings were at the 2017 Qatar Total Open and the 2017 Rogers Cup. Wozniacki won both matches in straight sets.

In 2006 she was the top seed at the Australian Open (junior girls' singles), but lost the final to eighth-seeded Anastasia Pavlyuchenkova. She was seeded second with partner Anna Tatishvili in the doubles tournament, but the pair was knocked out in the semifinals by the French-Italian pair of Alizé Cornet and Corinna Dentoni, who were seeded 8th. In February at the Memphis, she reached her first WTA Tour quarterfinal, beating Kristina Brandi and Ashley Harkleroad before losing to third-seeded Sofia Arvidsson of Sweden. Before Wimbledon Wozniacki won the Liverpool International Tennis Tournament, an exhibition tournament, beating Ashley Harkleroad in the final. Later that year she was given a wildcard to the qualifying draw at Wimbledon, where she was beaten in the first round by Miho Saeki. However, Wozniacki went on to win the Wimbledon girls' singles tournament, beating Slovak Magdaléna Rybáriková in the finals. In August, she reached another WTA Tour quarterfinal, this time at the Nordea Nordic Light Open in Stockholm. She defeated top-100 players Iveta Benešová and Eleni Daniilidou, then lost to eventual champion and third-seeded Zheng Jie.

Wozniacki won several junior tournaments in 2005, including the Orange Bowl tennis championship. She made her debut on the WTA Tour at Cincinnati's Western & Southern Financial Group Women's Open on 19 July 2005, losing to the top-seeded and eventual champion Patty Schnyder in the first round. In the Nordea Nordic Light Open, her other WTA tournament of the year, she lost to Martina Suchá in the first round.

Wozniacki had a career-high junior ranking of No. 2 in the world. She made her debut on the ITF Junior Circuit, the premier 18-and-under junior tour that is run by the International Tennis Federation (ITF), in October 2003 at 13 years and 3 months old. During her first month, she entered two Grade 5 events in Denmark, the lowest-level tournament on the tour. Wozniacki reached the final at both singles events, winning the second over compatriot Hanne Skak Jensen. With this success, she moved up to Grade 3 and Grade 4 tournaments, winning her first four singles events of 2004. Her win streak of five tournaments and 27 matches came to an end in April with a semifinal loss to Latisha Chan at the International Juniors Championships in Manila, her first event outside of Scandinavia as well as her first Grade 1 event. From this point on, Wozniacki only competed in Grade A and Grade 1 events, the two highest-level tournaments. She made her Grade A debut at Wimbledon before turning 14, losing her first main draw match. Towards the end of the year, Wozniacki won her first Grade A title at the Osaka Mayor's Cup.

Wozniacki, still suffering with the injury, was seeded eighth at the US Open, but did not advance past the first round. She lost in two sets to 96th-ranked Romanian Irina-Camelia Begu. As a result of the loss, Wozniacki dropped out of the top 10 for the first time in three years. Following her US Open disappointment, Wozniacki won her first tournament of the year in Seoul by defeating Arantxa Rus, Caroline Garcia, Klára Zakopalová, Ekaterina Makarova and Kaia Kanepi in the final. It was her 19th career title.

Caroline Wozniacki (R) (Danish: [kʰɑʁoˈliːnə vʌsniˈɑːkʰi] ; Polish: [vɔʑˈɲatskʲi] ; born 11 July 1990) is a Danish former professional tennis player. She reached world No. 1 in singles, the 20th in the Open Era, and the first woman from a Scandinavian country to hold the top ranking position. She finished on top of the rankings in both 2010 and 2011.

She played at Eastbourne, where she went one better than last year winning the title; she convincingly beat Camila Giorgi in round two. Next she got her first-ever win over Johanna Konta and then defeated Ashleigh Barty in the quarterfinals. Wozniacki then went on to save a match point to outlast Angelique Kerber to make her 53rd WTA final. In the final, she beat Aryna Sabalenka in two tight sets to win her 29th title of her career. The final marked her 600th career match-win. At Wimbledon, Wozniacki lost in second round to Ekaterina Makarova, after saving five match points.

At the Australian Open, Wozniacki defeated Gisela Dulko and 21st seed Alona Bondarenko on her way to the round of 16, where she lost to the eventual finalist and fourth-seeded Ana Ivanovic. At the French Open, Wozniacki was seeded 30th, making this the first Grand Slam tournament in which she was seeded. She again lost in the third round to the eventual champion and world No. 2 Ana Ivanovic. At Wimbledon, she reached the third round, but lost to second-seeded Jelena Janković.

Wozniacki was the 21st seed at the US Open. She defeated world No. 14 Victoria Azarenka in the third round, but lost to second-seeded and eventual runner-up Jelena Janković in the fourth round. At the China Open, she lost her opening match to Anabel Medina Garrigues. However, she teamed up with Medina Garrigues to clinch the doubles title, defeating the Chinese duo of Han Xinyun and Xu Yifan. It was Wozniacki's first WTA doubles title. At the Tier III AIG Japan Open Tennis Championships, she was the top seed for the first time on the WTA Tour, and won her third career title, defeating Kaia Kanepi of Estonia in the final. Wozniacki then took part in the Nordea Danish Open, in her hometown of Odense. After a string of good performances, she won the tournament, beating world No. 64 Sofia Arvidsson in the final.

Wozniacki was born in Odense, Denmark, the daughter of Polish immigrants, Piotr Woźniacki and Anna. Anna played on the Polish women's national volleyball team, and Piotr played professional football. The couple moved to Denmark when Piotr signed for the Danish football club Boldklubben 1909. Her older brother, Patrik Wozniacki, is a former professional footballer in Denmark.