Philadelphia will try to return to good form following last week's 1-1 draw with Montreal, but Chicago is still searching for its first victory of the season.
The Union controlled much of the proceedings against the Impact but could only manage a single goal, and Marco Di Vaio pounced late to split the spoils.
The Fire racked up their third consecutive draw with a 2-2 result against D.C. United. Jhon Kennedy Hurtado opened the scoring, and after D.C. came back to make it 2-1, but Quincy Amarikwa scored late to ensure the Fire would leave with a point.
The Union won two out of three meetings against the Fire last season, taking a pair of 1-0 decisions in May before Chicago picked up a 2-1 win on Aug. 3.
One player on each side could be facing his former club. Chicago center back Bakary Soumare was with Philadelphia before returning to the Windy City for a second Fire stint, and the Union aquired defender Austin Berry before the season.
Maurice Edu returns to Philadelphia after playing for the United States in midweek, becoming the first Union player capped while with the side. They'll have a no look up front after trading Jack McInerney to the Impact on Friday in exchange for Andrew Wenger.
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