Official release from Philadelphia Union
Additionally, the Union have waived goalkeeper Thorne Holder and defender Juan Diego Gonzalez.
A native of Mtwara, Tanzania, Khalfan has seen action in a total of 22 Major League Soccer regular season matches since the 2011 expansion team started play in the league. In 1,066 minutes, Khalfan notched a goal and four assists. The midfielder joined Vancouver midway through the 2009 USL First Division season, playing a total 58 games and 3,029 minutes.
Holder originally signed with the Union on March 1, 2011, seeing action in four reserve games against New York (4/10), New England (7/18, 9/8) and Columbus (9/18). The goalkeeper suffered a season-ending concussion during his last reserve game against the Crew.
Gonzalez came to the Union on August 5, 2010 after three years with Colombian club La Equidad, playing a total of seven games with the first team. In 2011, the Colombian defender started all 10 of Philadelphia's Reserve League matches but did not see action with the first team.