SEATTLE -- Hisashi Iwakuma was placed on the 15-day disabled list on Friday with a right lat strain, leaving a hole in Seattle's rotation.
The move before the series opener against Minnesota, retroactive to April 21, was a surprise, but Mariners general manager Jack Zduriencik said Iwakuma had been feeling fatigue in his throwing shoulder since his start last Monday against Houston.
Zduriencik said the plan was to see how Iwakuma was feeling after his bullpen session on Friday. When his shoulder didn't feel any better -- and he also felt stiffness in his back -- the decision was made to put him on the disabled list.
The Mariners said in a Saturday tweet that Iwakuma's Friday MRI revealed a Grade 1 strain of his right lat. He is expected to miss two to four weeks.
"[We] felt it best to back him off and put him on the DL to give him time to make sure this thing, it's a long season we don't want this thing to be an aggravated issue as we go through the next 5½ months," Zduriencik said. "We'll know a little more tonight. At this point we're hoping it's nothing more than shoulder fatigue and something very small."
The right-hander was scheduled to start the series finale against the Twins. Zdureincik did not announce who would start in Iwakuma's place, but the likely candidate would be Roenis Elias, now pitching at Triple-A Tacoma. Elias made 29 starts last season for Seattle and was 10-12 with a 3.85 ERA.
Iwakuma (0-1) has struggled in his three starts this season, giving up 12 earned runs in 16⅓ innings. Manager Lloyd McClendon was asked about Iwakuma prior to Friday's game but made no mention of a potential injury.
Seattle recalled left-handed reliever Lucas Luetge to take Iwakuma's spot on the 25-man roster. Luetge has made five appearances with Triple-A Tacoma this season.