The Mariners have also had to replace Roenis Elias in the rotation after he strained his left elbow in his last start on Sept. 16, with Taijuan Walker taking his spot for the last two turns.
Wilhelmsen has been outstanding in relief this year, and the former closer has converted into more of a long man when needed, with 16 of his 55 appearances having been two innings or more. He made one spot start just prior to the All-Star break, taking the loss against the Twins on July 10 after allowing two runs (one earned) on one hit with three walks in 2 2/3 innings.
"It's clearly different, but I'm not expected to go seven innings," Wilhelmsen said. "I'll just do the same thing I did the last start. I felt fine after and before that. So hopefully we can sneak a win in."
McClendon debated between Wilhelmsen and Dominic Leone, and hopes to get several innings out of Wilhelmsen before turning the game over to the rest of the bullpen. McClendon said Young will be available to pitch relief in that game if needed.
McClendon earlier in the season expressed intrigue about Wilhelmsen's potential as a starter, but that talk has quieted. The 6-foot-6 right-hander said nobody has spoken to him about his possible role for next year.
"Not yet," he said. "We still have games here. And that's where my head and heart is right now. So wherever that is, one day at a time."
Wilhelmsen struggled last year, lost his closer's job midseason and finished the season with a 4.12 ERA in 59 innings over 59 outings with 45 hits, 33 walks and 45 strikeouts. This year he's been one of the bullpen's most-reliable members, as he's put up a 2.10 ERA in 77 innings while allowing 44 hits with 34 walks and 71 strikeouts.
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.