Lee competed in the 2002 Asian Games where he showed signs of promise as an ace singles player for Team Korea. In the men's team event, Lee dominated the opponents he faced in the tourney, completing all three matches less than 30 minutes and allowing only seven points in the semifinals and eight in the final. Team Korea eventually won their first men's team gold medal since 1986 when Park Joo-bong and Kim Moon-soo led the team.
At the 2003 Sudirman Cup held in Eindhoven, Netherlands, Lee helped his team to win its third Sudirman Cup title, winning all three singles matches. Though lots of great doubles players from South Korea had won numerous international competitions, Team Korea had always struggled to win the Thomas and Sudirman Cup competitions due to the lack of top men's singles players. However, Lee, the winner of the 2003 Swiss Open, showed spectacular performances through the Sudirman Cup tourney, not dropping a single set. In the semifinal, Lee defeated 2001 World Championship runner-up and 2001 All England Open champion Peter Gade 2-0, which led his team to a 3-2 victory over Denmark. Lee won another 2-0 upset victory over world number one ranked Chen Hong in Game 1 of the South Korea's final team event against China.
After the 2008 Olympics, Lee announced his retirement from international badminton and only competed in national competitions. However, in April 2010 he came out of retirement after much persuasion from the coach and teammates to fill the void of singles players in the Team Korea squad. In May 2010, Lee participated in the 2010 Thomas Cup and played in two singles matches.