The Pirates scored first on an Andrew McCutchen single after their first three runners reached base in the first, but the Cardinals came screeching back for three runs in the bottom of the inning.
The Pirates' first three runners then all reached again in the top of the second, and the Pirates got three more runs to take a 4-3 lead. But that was all the scoring they would do, and the Cardinals scored in the third and fourth to take a 5-4 lead, then tacked on two runs against Chris Resop in the seventh.
Karstens' afternoon ended with five runs allowed in 3.2 innings, while Kyle Lohse picked up the win after allowing four runs, two earned, in five innings.
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