De Rosario did most of the work on Wolff's goal, as he collected a pass from Andy Najar on the left side of the Philadelphia penalty area and wound his way to the byline, where he managed to draw two visiting players to him before crossing the ball to Wolff, who turned the ball in from two yards out for his fourth goal of the season.
D.C. United had the first good chance of the evening as Chris Pontius sent a downward header wide of Faryd Mondragon's right post in the 2nd minute. After a slow start, Philadelphia slowly found their way into the match and Danny Mwanga forced Bill Hamid into a diving 19th minute save to push the Congolese striker's attempt around the left post. The home team almost scored a minute later as Pontius forced Mondragon to lunge to his right to tip the winger's drive to safety. In the 24th minute, it was Wolff's turn to sting Mondragon's palms with an angled shot from inside the area, but the Colombian netminder was equal to the task and the Union were able to clear away the rebound.
Philadelphia's best chance of the match came in the 36th minute as Sebastian Le Toux was sent clear down the right wing, but while the Frenchman was able to dink the ball past the onrushing Hamid, he could only manage to place the ball just wide of Hamid's right post.