Folks may have wondered what all the preseason power fuss was about until Michael Morse decided to show them with one third-inning swing.

Up to that point, the Mariners' vaunted middle-of-the-order additions of Morse and Kendrys Morales had failed to hit a ball beyond the infield in this very early 2013 season. But that changed in a hurry Tuesday night when Morse connected for his first of two home runs, a three-run, opposite-field shot to help send the Mariners to a 7-1 win over the Oakland Athletics.

Mariners starting pitcher Hisashi Iwakuma tossed six innings of two-hit ball, striking out seven, to cruise to one of his easier victories in the majors. But it was mainly about the offense in this one, with Morse putting the finishing touches on the night with a rocket blast over the center-field fence in the ninth off A's closer Grant Balfour.

"I got two good pitches to hit, I didn't try to do too much and I got the barrel on the ball," said Morse, who hit a club-record nine home runs in spring training.

The power surge by Morse was only part of the offensive story, because the Mariners also drew eight walks. Kyle Seager reached base five times and had a pair of doubles, one driving in an eighth-inning run.

All the pitch-taking by the Mariners in their second straight win here helped them burn through six Oakland pitchers, with two games still remaining in the series.

The Mariners, for their part, got three scoreless frames from Carter Capps and Oliver Perez in relief, largely sparing the bullpen from extended work once Iwakuma was pulled after 88 pitches.

But it was Morse's third-inning shot off A's starter Jarrod Parker, lined hard over the right-field wall, that changed the game's complexion. A crowd of 15,315 at the Coliseum had seen Oakland take a 1-0 lead a half-inning earlier on a Yoenis Cespedes home run, but was stunned into silence as Morse circled the bases.