Junior Fa

Late January 2017, it was announced Fa had agreed to terms signing a three-year deal, which included clauses for a possible fourth under the tutelage of Lou DiBella. DiBella, a former boss of HBO's Boxing set up and looking after seventy fighters, including WBC heavyweight champion Deontay Wilder, where Fa would be joining him as DiBella's only other heavyweight fighter. The deal would see him fight at least three times in the United States per year, flying over fifteen days before every bout. His first challenge would be on the undercard of Wilder's title defense against Gerald Washington on 25 February at the Legacy Arena in Birmingham, Alabama. Taking on American journeyman Keith Barr over six rounds.

Fa turned pro in February 2016, where he featured at The Night of the Freaks from ASB Stadium, Auckland. After taking three years out of the sport to have a family, Fa decide to return to the sport. Assembling an impressive team, Lolo Heimuli as coach, former New Zealand Olympic sprinter Mark Keddell as manager, Shane Cameron as mentor along with input from strength and conditioning guru Angus Ross. Fa fought veteran Richard Tutaki, winning in a first-round knockout. Something Fa's amateur rival, Joseph Parker couldn't do as it took him three rounds in his third bout. In only his second professional fight, Fa was added to the Taranaki Explosion Fight Night card on 2 April. Fa showing he was far too good for Clint Foa'i whose corner threw the towel in during the first round after their fighter was hit hard in the ribs, his pain obvious. Fa fought in quick succession after another successful victory over Australian based Jayson Aloese, participating in the Royal Rampage event. Aloese whom was undefeated as both a corporate boxer and a professional, lost on points in a four-round fight by unanimous decision. Fa remained unbeaten, extending his record to four an zero. In the co-main event, New Zealand prospect Fa won his second unanimous points victory in a one-sided contest against fellow New Zealander Junior Pati. Fa landing big punches and huge shots, but could not end the fight early with Pati being remarkably durable. Fa also switched coaches, learning off Henry Schuster.

In their fourth contest, Fa and Parker fought in a do-or-die opportunity to secure a place at the 2012 Summer Olympics during the Oceania Boxing Championships in Canberra, Australia. Parker had four opponents in the super-heavyweight division, one being Fa. Parker was eliminated, Fa claiming a closely fought three-round encounter eleven points to eight. He dropped the first round 2–1 but came back strongly in the second to secure a decisive 3-point lead that he protected when the final three-minute joust ended in stalemate.

Fa was drafted for two seasons of the World Series of Boxing. His first season was with the Indian Mumbai Fighters Franchise as a mid season sign up for the 2011–12 season. He had a successful season and was ranked in the top 8 heavyweights for the series. His second season was during 2012–13 where he was drafted by the British Lionhearts where he fought the likes of Oleksandr Usyk and former multiple Olympic silver medalist, Clemente Russo. He was based in Sheffield, England training alongside the likes of Anthony Joshua and Joe Joyce. His first encounter with Joshua was when he trained with him back in mid-2011 when Joshua was just starting out.

Fa and Joseph Parker fought four times during their amateur careers, with two victories and two defeats each. Their first encounter was at the 2009 Boxing New Zealand National Championships held in Rotorua. The pair competed in the super-heavyweight final, Fa defeating Parker 8–4. Fa was also awarded the Bill O'Connor Cup for the youngest senior titleholder. A month later Parker forced a second-round standing eight count and a points win over Fa in a Samoan Tsunami Boxing appeal event at the North Shore Events Centre, organized by David Tua. On 12 June, they meet for a third time in an amateur world-class contest rematch. It showcased as the main event at The Night of the Young Champions from ABA Stadium in 2010. Parker won by a large margin of twelve points.

At the Oceanian Amateur Boxing Championships, Fa featured in three consecutive events. In 2008 in Apia, Samoa he won a silver medal. Fa fought for a qualification spot and progression into the 2008 Summer Olympics. He began with a points decision victory over New Zealand senior North Island champion, Isikeli Maama in the quarter-finals. He followed up with another win over Australian Steven Rudic before losing out to Daniel Beahan on points in the final to gain gold. During 2010, Fa return home with a gold medal from the tournament held in Canberra. He controlled an emphatic win over the host nations, Alexey Mukhin. Establishing himself an 8–1 score in his favor. He again had a chance to make it to the Olympics after having to win an Oceania gold medal to secure a position. Unfortunately, Fa instead won silver. He started off with a close win over New Zealand up and coming prospect and later rival, Joseph Parker. He continued his winning streak with a first-round technical knockout over Jubilee Arama in the semi-finals but lost the final against Johan Linde to settle for second place.

For much of his amateur career, Fa began under the guidance of coach and trainer Lolo Heimuli. Heimuli brought Fa to his Balmoral Lee Gar Gym in 2006 after discovering his coach failed to show at his first amateur fight. Being born and raised in Papakura, New Zealand, Fa decided to represent Tonga as an amateur. He was the flag bearer for Tonga on two occasions at the Commonwealth Games.

In March, Fa prepared for the vacant New Zealand Professional Boxing Association heavyweight title against Daniel Tai, at the ABA Stadium in Auckland. It would be his first title shot. Tai, an Auckland-based fighter, had been fighting professionally since the year 2000, whilst he boast a record of 22 wins and 9 losses. With only one loss coming by knockout, in 2001, by legendary Australian champion Danny Green. With the title being vacant for almost five years and last held by Sonny Bill Williams, this was Fa's most difficult fight of his career to note as he was hampered by a back injury and forced to live off the jab. Tai applied pressure and landed several clean blows throughout the bout Tai, however, Fa did enough to win most of the rounds. The judges were divided, however, with one judge scoring a draw in a disappointing majority decision win to Fa.

Uaine Fa Junior (born 19 October 1989) is a New Zealand professional boxer. He has held the WBO Oriental interim heavyweight title since 2018. As an amateur he represented Tonga at the 2010 Commonwealth Games, winning a bronze medal in the super-heavyweight division; he also represented Tonga at the Oceania Championships, winning gold and multiple silver medals. His knockout-to-win ratio stands at 62%.