NEW YORK -- Though the Mariners haven't made anything official yet because he's still on the 15-day disabled list, All-Star right-hander Hisashi Iwakuma will make his regular-season debut on Saturday against the Astros during Seattle's three-game set at Minute Maid Park.
Iwakuma will need to be added to the 25-man roster prior to Saturday's 1:10 p.m. PT game in Houston. The 33-year-old missed all of Spring Training after spraining a tendon in his right middle finger. He threw four innings in a Minor League rehab start last Sunday for Triple-A Tacoma, and he will rejoin the Mariners rotation a month into the season.
Iwakuma's addition will be a big boost for a Mariners rotation that also has James Paxton, Taijuan Walker and Blake Beavan on the disabled list. Iwakuma was third in the American League Cy Young Award voting last year after going 14-6 with a 2.66 ERA in 33 starts.
Iwakuma will slot in behind Felix Hernandez, who'll pitch the opening game of the Houston series after having his Thursday start against the Yankees pushed back by a Wednesday rainout in New York.
Manager Lloyd McClendon said he considered starting Hernandez on Thursday, given his outstanding history against the Yankees. McClendon instead kept the rotation in order, with rookie Roenis Elias getting the nod in the series finale in the Bronx after his Wednesday start was postponed.
"I wanted to give him an extra day, and it also gives Elias an extra day. It just made sense," McClendon said. "Felix has been taxed quite a bit and has pitched on regular rest for quite a while. This is an opportunity to get him where we need him to be. His last two outings have not been sterling outings, I think we'd all agree. So this is a chance to freshen him up and get him back on the right track."
Hernandez was 3-0 with a 1.91 ERA with three walks and 39 strikeouts in his first four starts of the year, but he posted an 0-1 record with a 3.46 ERA, four walks and eight strikeouts in back-to-back losses to the Astros and Rangers his past two outings.
The tentative pitching plan for the Mariners calls for Brandon Maurer to follow Iwakuma on Sunday in Houston. The Mariners would then head to Oakland and hand the ball to Chris Young on Monday, Elias on Tuesday and have Hernandez and Erasmo Ramirez pitch in Wednesday's doubleheader. Ramirez currently is with Triple-A Tacoma.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.