Yi attended UCLA where he was named the Pac-10's Freshman of the Year and was a second team all-conference performer for the Bruins in 2000. He was also selected to Soccer America's All-Freshmen Team and was named one of Five Players to Watch by the Missouri Athletic Club. Yi was named to the NSCAA All-American Third Team and was a MAC Hermann Trophy nominee as a sophomore in 2001. Yi started 41 games in his two-year playing career at UCLA.

A former midfielder and defender, Yi played three seasons (2002-05) with Antwerp FC of the Belgian Jupiter League, a feeder club of Manchester United. He made his Antwerp debut against Club Brugge in 2002 and the next season was voted as the Man of the Match for his outstanding play in a game against Mons-Bergen.

Yi was picked up by FC Dallas in an MLS weighted lottery in January 2005 and went on to play three seasons with FC Dallas. Yi made his MLS debut on Sept. 24, 2005 with a start against San Jose.

As an amateur, Yi was a member of the U-17, U-20 and U-23 U.S. Youth National teams and started all five games during the 1999 World Youth Championship in New Zealand, helping the U.S. team finish fourth. He also played in all three games during the 2001 FIFA World Youth Championships held in Argentina.

Yi earned a total of 57 career caps with various U.S. youth national teams, including six with the U-23 team, 12 with the U-20 team and 39 with the U-17's. Yi made his international debut with the U-17's against Mexico on Feb. 13, 1998.

Yi has strong roots in the Maryland area and attended The Country School in Easton, Georgetown Prep his freshman year and then McDonogh High School in Owings Mills, where he earned All-Met and all-county honors in 1998. He was a Parade All-American in 2000 and a two-time NSCAA All-American. He played club soccer with FC Potomac with future MLS players Kyle Beckerman and Oguchi Onyewu.

Yi was also part of the inaugural class of the U.S. Soccer Federation's Bradenton Academy, along with players such as Landon Donovan, DaMarcus Beasley and Onyewu.