Kieran Tierney

On 8 August 2019, Tierney signed for English Premier League team, Arsenal for a reported £25 million fee. Tierney missed the early part of the 2019–20 season, having undergone a double hernia operation in May 2019. He made his first-team debut for Arsenal in a 5–0 win against Nottingham Forest in the EFL Cup on 24 September. Tierney assisted the first goal in a 4–0 home win against Standard Liege scored by Gabriel Martinelli a week later. He made his first appearance in the Premier League on 27 October, in a 2–2 draw with Crystal Palace. His season was further disrupted after suffering a dislocated shoulder in the game against West Ham United.

In November 2019, Tierney withdrew from the Scotland squad ahead of their UEFA Euro 2020 qualifiers against Cyprus and Kazakhstan due to an alleged ongoing hip injury, despite now playing regularly for his club, Arsenal.

Tierney played in Celtic's victory over Aberdeen in the 2018 Scottish League Cup Final on 2 December 2018. Soon afterwards a hip injury meant that he was ruled out of action, returning on 24 February 2019. He then suffered from a hernia, which subsequently required surgery.

In October 2018, Tierney scored a decisive own goal in a 2–1 loss to Israel in a UEFA Nations League fixture. Speaking after the game, Robertson said that both he and Tierney were being played out of position in the 3–5–2 system adopted by Alex McLeish to accommodate both players.

On 22 January 2017, after missing three months, he made his long-awaited return to the Celtic team in a Scottish Cup tie against Albion Rovers. Tierney was crowned PFA Scotland Young Player of the Year for the second consecutive season on 7 May, making him the first to achieve this since Craig Levein in 1986. He suffered a jaw injury early in the 2017 Scottish Cup Final and had to be substituted for treatment. Celtic won the match 2–1 to complete a domestic treble and perfect season. In spite of his lengthy injury absence, he featured in 40 matches during the campaign.

On 8 August 2017, Tierney was named as captain while also moving to central defender to command a back line of teenagers in a Scottish League Cup fixture against Kilmarnock; Celtic won the game 5–0, with Tierney providing an assist and scoring with a "wonderful strike" from 40 yards. On 30 October, a week after scoring in an important league victory away to closest challengers Aberdeen, he extended his contract with Celtic until 2023.

Due to Tierney's greater adaptability compared to fellow left-back Andrew Robertson, Tierney was deployed at right-back in Scotland's matches against Slovenia, Lithuania and Slovakia, and on the left of a three-man defence in the fixture at home to England during World Cup qualifiers in 2017.

Tierney was selected as Scotland captain for a friendly match against the Netherlands in November 2017, where he played as a central defender in a 1–0 defeat.

Tierney enjoyed a breakthrough season in 2015–16, appearing in over 30 matches and displacing the more experienced Emilio Izaguirre as first-choice left back. For his performances he was awarded with both the Players' and Writers' Young Player annual awards, while Celtic also won the league title. Despite interest from Premier League clubs, Tierney signed a new five-year contract on 24 June 2016, keeping him at Parkhead until 2021.

After making his first appearances in the group stage of the UEFA Champions League, Tierney suffered ankle ligament damage during training on 27 October 2016 and was initially ruled out of action for two months. During the layoff, which caused him to miss the League Cup Final, he received treatment on a recurring shoulder injury and attended several Celtic matches as a typical supporter in the company of his childhood friends.

Tierney received his first call-up to the senior Scotland squad on 10 March 2016 for a friendly against Denmark. Tierney played for the first half of the match, which Scotland won 1–0 at Hampden Park; he was replaced at the break by his Celtic teammate Charlie Mulgrew.

Tierney made his competitive senior debut for Celtic on 22 April 2015, coming on as an 81st-minute substitute in a Scottish Premiership match against Dundee. He made one further first team appearance that season, playing over an hour in a league match away at St Johnstone.

He progressed through the various youth ranks and earned a reputation as a dependable wide player in the club's development squad, both in defence and attack. He travelled with the first team squad on a pre-season trip to Finland in August 2014, and made his debut in a friendly against Tottenham Hotspur there. Although Celtic lost, Tierney described his first appearance for the first team as a "dream come true". He continued to play in the development squad throughout 2014–15, and in October 2014 during a Development League match against Heart of Midlothian he scored a goal from the edge of his own penalty box.

By the end of the season, he had collected further personal accolades—winning both the Players' and Writers' Young Player awards for the third campaign in succession—and performed a major role in securing a historic 'double treble' for the club, making more than 50 appearances and playing the entirety of the domestic cup finals, both being 2–0 wins over Motherwell.

Kieran Tierney (born 5 June 1997) is a Scottish professional footballer who plays for Premier League side Arsenal and the Scotland national team as a left back. Born on the Isle of Man, Tierney moved to Lanarkshire at a young age. He came through the Celtic youth system and made his first team debut in April 2015, and his full international debut in March 2016. He joined Arsenal in August 2019 for a fee reported at £25 million, a record amount both for a Scottish national and for a player from the Scottish league.