Early Career, Major League Soccer Serna began his career in his native Colombia with
Cortuluá and
Independiente Medellín, before moving to MLS with the expansion Fusion in 1998. He became the one constant in Miami's lineup for the four years of the team's existence, leading them in goals in points his first three seasons with the club. Overall, he ended up with team records of 100 games, 52 goals, 36 assists, and 140 points in the regular season, and added a goal and an assist in six playoff games. In 2001, he was named to the
MLS Best XI. The Fusion was contracted before the 2002 MLS season, so Serna was picked 4th overall in the
2002 MLS Allocation Draft by the
MetroStars, who traded
Mark Chung to obtain that pick. Diego only played eight games for the Metros, scoring one goal. He was traded to the
New England Revolution in a six-player deal midway through the season, the other principal of which was
Mamadou Diallo. Serna only scored one goal for the Revs in five games before his season was ended by an injury. He went back to Colombia to
Atlético Nacional and Independiente Medellín, before returning to MLS in the middle of the 2003 season for a stint with the
Los Angeles Galaxy, scoring three goals in ten games.
Return to South America After spending some time playing in his native
Colombia with
Once Caldas and
Deportes Quindío, Serna returned to MLS with the
Colorado Rapids in August 2005. He then played for
Macará of Ecuador in 2006, before joining
Fast of Brazil in 2007 and 2008.
USL Although Serna was an excellent goal-scorer in MLS, after the Miami Fusion was disbanded, he never reached his maximum potential in the league, electing to play in various leagues throughout South America, contributing to his advancement as a well-rounded, professional veteran. In 2009, he returned to Florida, signing with
Miami FC scoring a goal, and providing two assists, ensuring a victory in his homecoming game.
USL/MISL (Indoor) Serna signed with
Syracuse Silver Knights of the American
Major Indoor Soccer League on October 11, 2011. He made his debut in a 16–15 win over the
Rochester Lancers (2010). He was released from the team January 6, 2012.
NAL On May 5, 2014, at age 40, Serna signed with
Miami Dade FC to play the 2014 season. ==Honors==