He didn't have to go through the Yankees lineup, though.
Iwakuma will face perhaps his biggest test since joining Seattle when he goes up against New York in the rubber game of a midweek series at Safeco Field.
In his last start, the former Japanese star allowed two runs in six innings on six hits and a walk while punching out seven Rays.
Taking the mound opposite Iwakuma will be righty Ivan Nova, who has won just one of his past five starts.
He pitched his way into a no-decision in his latest outing, lasting 6 2/3 innings and allowing nine hits and two walks that resulted in just a pair of runs to go with six strikeouts against Oakland.
In the five-game stretch, Nova pitched a combined 32 innings and allowed 13 earned runs, but his defense cost him another four unearned runs.
Yankees: Ichiro to see time in left field
After acquiring Japanese star Ichiro Suzuki, New York suddenly had to make a decision of what to do in right field once Nick Swisher returns from a strained hip flexor.
Though he's played left field just once in his career, Ichiro was told he'd be moved over and manager Joe Girardi expects an easy transition.
"I think with the way our ballpark is, it just makes sense to put him in left and keep Swish in right," Girardi said.
But for the time being, Ichiro finds himself playing at his natural position in right field, though one thing he isn't used to was batting in the bottom third of the lineup. He has responded well by going 2-for-7 batting eighth in his first two games for New York.
Mariners: Club fills out roster
After trading away Ichiro and optioning Justin Smoak to Triple-A Tacoma, Seattle had a pair of empty spots on its roster to fill.
The club elected to recall Mike Carp, who was sidelined because of a shoulder injury, from his rehab assignment in Tacoma. He went 0-for-3 with two strikeouts at the plate in Tuesday's 4-2 win over the Yankees.
"I want to make sure we keep Carp healthy and strong and where we can see his swing the way it should be," manager Eric Wedge said. "Hopefully he can come up here and help us."
Outfielder Trayvon Robinson took the other roster spot and is seeing his first action in the Majors this season after hitting .265 with nine homers and 41 RBIs with Tacoma.
Yankees pitcher Joba Chamberlain tossed a scoreless inning, retiring all three batters he faced, Tuesday in a rehab start for Class A Tampa.
New York third baseman Alex Rodriguez broke his left hand Tuesday when he was hit on the left hand by a pitch from Felix Hernandez.
Since giving up the deciding run in a 14-inning game against the Rays, Mariners closer Tom Wilhelmsen has converted his last three save opportunities, including Tuesday when he retired all three Yankees batters he faced.