Iwakuma (6-1) allowed seven hits and struck out five in his 7 2/3 scoreless innings. Tom Wilhelmsen worked a perfect ninth for his 12th save.
Seattle posted a 7-1 win over San Diego Thursday in a game that saw Felix Hernandez give up three hits in eight innings. The Mariners have won four out of six.
All of the Seattle runs came in the sixth inning, during which Kendrys Morales hit a two-run homer and Jesus Sucre delivered an RBI single.
Mile Pelfrey (3-6) surrendered all three runs on six hits in 5 1/3 innings as the Twins fell for the first time in five outings.