FC Dallas appeared on its way to a third straight 1-0 victory when Brek Shea scored his first career goal in the 13th minute on assists from Atiba Harris and Jeff Cunningham.
Philadelphia had plenty of scoring opportunities, especially in the first half, but couldn't convert on nine shots on goal.
FC Dallas (2-1-5) goalkeeper Kevin Hartman, a four-time All-Star, entered the game with a 0.67 goals-against average, second in the league.
The Union (1-5-1) had lost four straight after beating D.C. United on April 10. They were playing just their second home game, before 25,038 fans at Lincoln Financial Field, home of the Eagles.
The Union have 12 of their first 15 games on the road before moving into their new stadium in nearby Chester on June 27.
Mwanga was the first overall pick in the MLS draft out of Oregon State.
(Copyright 2010 Philadelphia Union. Reprinted by permission)
