Buck's blast in the second inning off struggling Phillies starter Roy Halladay gave the Mets a 3-0 lead and set the tone for the game.
Harvey (2-0) followed up a seven-inning, one-hit performance in his previous start with another solid effort, limiting the Phillies to one run on three hits while striking out nine and walking two.
Phillies ace Halladay (0-2), meanwhile, was hit hard in his second straight outing, yielding seven runs on six hit over four full frames.
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