Wainwright (8-3) yielded eight hits, didn't issue a walk and struck out 10 in the 106-pitch performance, lowering his ERA to 2.33 en route to his third win in three starts.
Giants starter Madison Bumgarner (4-4) was tagged for five runs on six hits in six frames.
Andres Torres supplied the only RBI for San Francisco, which fell for the fifth time in six contests.
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