The Red Bulls were looking to grab a lead late in the closing seconds of the first half when Jonathan Steele sent a dangerous cross into the box, where Espindola got a head on it.
But MacMath pushed it over the crossbar for a save.
The Union goalkeeper also stopped a Brandon Barklage header late in the game as Philadelphia (10-7-8) fell to fourth place in the Eastern Conference after Montreal's victory over D.C. United earlier Saturday.
Conference co-leading New York (11-8-6) moved to 1-1-1 in three meetings with the Union this season.
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