Casey sent home Sebastien Le Toux's cross in the 55th minute for Philadelphia (8-9-9). Two minutes later, Union goalkeeper Zac MacMath saved a close-range attempt by an unmarked Gilberto. MacMath helped Philadelphia earn its first shutout win since mid-March.
Toronto (9-10-6) hasn't won in four matches and will host Philadelphia on Saturday. Ryan Nelsen was fired as coach Sunday, a day after a loss to New England.