Millwood (4-8) yielded one unearned run on six hits, walked one and struck out three in notching his first victory over a span of nine starts. The right-hander placed 65 of his 106 pitches for strikes.
Jesus Montero put the Mariners ahead with a two-run homer in the third inning. Miguel Olivo and Mike Carp added RBI as Seattle downed Kansas City for a third straight time.
Tom Wilhelmsen notched his 13th save despite allowing an RBI triple to Lorenzo Cain in the ninth inning.
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