Kacper Przybylko scored on either side of halftime after Romell Quioto scored and was ejected inside the first 20 minutes as the Union won their third straight match and returned to second place in the Eastern Conference.
Ray Gaddis was rested as he recovers from a minor injury and Jose Martinez was suspended for yellow card accumulation. Matt Real and Warren Creavalle came into the starting lineup as Jim Curtin sought to maintain a solid defense despite missing both starting fullbacks.
The Impact dealt Philly an early blow from a well-placed set piece. Quioto spun a low shot through a hole in the Union wall and past Andre Blake in the fifth minute.