Chicago (1-3-0) scored in the 37th minute when Adailton slipped the defense, deftly cut in front of goalkeeper Rais M'bolhi and flicked a header into the open goal off a set piece from the left wing by Harrison Shipp.
Philadelphia (0-2-2) played the final 20 minutes down a man after Fred was shown a red card for throwing a punch at Shipp after a tackle at midfield. The Union were already missing four regulars for the game, with Cristian Maidana, C.J. Sapong and Conor Casey out with injury, and Zach Pfeffer sitting out a suspension.
Sean Johnson wasn't forced to make a save in the shutout. The Union managed just seven shots, none on goal.