Ulsan Hyundai Horang-i Lee recorded seven goals and nine assists during 18 appearances in the
2002 K League, showing his talent in his first professional season. After becoming a World Cup semi-finalist and the
top assist provider of the K League at the age of 19, he was named the
Asian Young Footballer of the Year by the
Asian Football Confederation. In July 2003, he joined
Real Sociedad, the runners-up of the
2002–03 La Liga, becoming the first Korean to play in La Liga. However, after a mediocre season, he was loaned out to fellow La Liga side
Numancia, and ultimately returned to South Korea. He was unable to score in the La Liga in his two years there. Lee rejoined Ulsan in mid-season. He especially scored a hat trick in the first leg of the
championship final. He was subsequently named the K League's
Most Valuable Player.
Feyenoord In the summer of 2007, Lee joined
Feyenoord of the
Eredivisie. He got the second chance to play in Europe, but failed to adapt to the Netherlands. While he competed in Feyenoord, he was scammed in his country, and took a two-week vacation to solve the problem. He had difficulty concentrating on football due to his case of fraud, and Feyenoord officially announced Lee's loan to South Korean team
Suwon Samsung Bluewings on a one-year deal in July 2008.
Loan spells Even in Suwon, his stint was ill-received: he performed poorly, had clashes with the coaching staff, and was banished from the K League. After a few months, Suwon released him from the banishment, and he could be loaned to
Jeonnam Dragons on 26 February 2009. In June 2009, he claimed he couldn't reject his transfer according to his contract with Feyenoord if another club suggest a high salary to him, and he joined a Saudi club
Al-Nassr in the middle of the season. However, the dual contract did not exist in reality, and he was prohibited from joining the K League again after Jeonnam got to know the truth.
Incheon United In March 2010, he left Al-Nassr because the club did not give his wages for three months. He joined a
J1 League club
Omiya Ardija, and played in Japan for a year and a half. After leaving Omiya Ardija, Lee did not join any foreign professional club for a year, and hoped to play in South Korea. Jeonnam Dragons released his indefinite banishment after watching his behavior including three apologies at the stadium. On 31 March 2013, he came back to the
K League with
Incheon United in a game against
Daejeon Citizen 1,381 days after the last game with Jeonnam. On 5 November 2015, he announced his retirement as a player. His retirement ceremony was held at half time of a World Cup qualifier between South Korea and
Lebanon in March 2016. ==International career==