Lee Kang-in

He was born on 19 February 2001 in Incheon, the youngest of three children. His father Lee Woon-seong was a taekwondo instructor in Incheon and a big football fan (especially of Diego Maradona).

In 2007, the six-year-old Lee was featured in the third season of the KBS N Sports reality football show Fly Shoot Dori (Korean: 날아라 슛돌이; meaning: Fly Shooting Kid). After his exceptional performance, he passed through Yoo Sang-chul's youth academy and in 2009 joined the Incheon United FC U-12 youth team. Lee later attended Seokjeong Elementary School in Incheon and played for Flyings FC. In January 2011, he went to Spain under the recommendation of his youth team coach and underwent tests for the Villarreal CF and Valencia CF youth teams.

Lee joined Valencia CF's academy in July 2011. On 15 December 2017, he was called up to Valencia CF Mestalla. He had his debut on 21 December 2017, in a match with Deportivo Aragón, being substituted in the 82nd minute.

He had his first assist on 17 February 2018, against UE Llagostera, being substituted in at the 76th minute and assisting in extra time. He had his first goal on 6 May 2018, starting against CE Sabadell FC.

He made his first team debut on 30 October 2018, starting and playing 83 minutes in a 2–1 win over CD Ebro in the Copa del Rey, becoming the youngest Korean footballer to debut professionally in Europe.

Lee made his La Liga debut on 12 January 2019, substituting in for Denis Cheryshev in the 86th minute in a 1–1 draw with Real Valladolid during 2018–19 season. At 17 years, 10 months, and 24 days, Lee became the second youngest player in the 18–19 La Liga after Ander Barrenetxea from Real Sociedad who debuted at the age of 16 years, 11 months, and 24 days. He also became the youngest ever non-Spanish and the first Asian league debutant for Valencia, as well as the fifth Korean to play in La Liga (after Lee Chun-soo in 2003 for Real Sociedad, Lee Ho-jin in 2006 for Racing de Santander, Park Chu-young in 2012 for RC Celta de Vigo and Kim Young-gyu in 2013 for UD Almería).

On 30 January 2019, Lee officially joined the Valencia first-team, receiving jersey number 16.

On 17 September 2019, Lee made his UEFA Champions League debut as a late substitute for Rodrigo in a 1–0 win against Chelsea, becoming the youngest ever Korean to debut in the competition at the age of 18 years and 6 months, a record previously held by Jeong Woo-yeong. He also became the 5th youngest ever to debut for Los Ches in the same competition. On 25 September 2019, he scored his first La Liga goal in a 3–3 draw against Getafe, to become the youngest non-Spanish to score for Valencia, aged 18 years and 219 days old, breaking the previous record of Mohamed Sissoko who scored in the 2003–04 UEFA Cup; and the third youngest ever, only behind Juan Mena Tormo and Fernando Gómez. His record as the youngest non-Spanish goalscorer for Valencia was broken the following season by American teammate Yunus Musah.

Lee was selected to play for the South Korea U-20 football team in the 2019 FIFA U-20 World Cup and played in every group and knockout match, leading his team to a historic runner-up finish in the tournament and scoring two goals and four assists in seven games. As a result, he received the Golden Ball award as the tournament's best player.

Lee received his first call up to the senior South Korea national football team in March 2019 for friendlies against Bolivia and Colombia, and became the 7th youngest to be in the South Korea national football team. On 5 September 2019, Lee made his international debut in a 2–2 draw friendly match against Georgia as a starter.

On 13 September 2020, Lee became the youngest player, aged 19 years and 207 days, to assist two goals in a La Liga match in the 21st century, in a 4–2 win over Levante, breaking the previous record of Juan Mata in 2008, aged 20 years and 150 days.