Iwakuma faced 15 batters in his 56-pitch outing against the Eugene Emeralds, finishing with three strikeouts and no walks. He threw a perfect first inning before surrendering a single to designated hitter Justin Marra to begin the top of the second. He then retired three straight to get out of the inning unscathed.
The only damage against Iwakuma came in his fourth inning. Eugene right fielder Ian Happ homered to right to lead off the inning and second baseman Frandy Delarosa doubled to right two batters later for the Emeralds' third hit of the night. Iwakuma then got catcher Alberto Mineo to fly out for the second out of the inning before being lifted for right-hander Troy Scott.
The outing was Iwakuma's first since an April 20 start against the Astros, in which the 34-year-old allowed four runs in 5 1/3 innings. He was placed on the disabled list four days later with a strained right latissimus dorsi muscle.
Mariners manager Lloyd McClendon said before Friday night's game that he expects Iwakuma to make his next rehab start for Triple-A Tacoma, which returns home Tuesday for an 11-game homestand.
Andrew Erickson is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.