But unless general manager Jerry Dipoto has some tricks up his sleeve, the obvious likelihood will be for 24-year-old right-hander Taijuan Walker to be recalled from Triple-A Tacoma after making two starts for the Rainiers.
Walker threw 6 1/3 scoreless innings in his last outing for Tacoma on Thursday and is tentatively lined up to pitch again Tuesday for the Rainiers against Las Vegas. Walker is 4-7 with a 4.10 ERA in 17 starts for Seattle this season, but was sidelined for a month in July with tendinitis in his right arch.
Walker has pitched just once for the Mariners since July 5, allowing six runs on seven hits in four innings against the Angels on Aug. 6 before being sent to Tacoma.
The Mariners also expect to add left-hander James Paxton back to the rotation Thursday when he'll come off the 15-day DL to face the White Sox as Seattle opens a seven-day road trip.
Seattle's rotation has been in flux of late, but the return of Paxton and Walker behind veterans Felix Hernandez and Hisashi Iwakuma would solidify things.
Cody Martin is likely be to be optioned back to Tacoma after making his second spot start in Monday's series opener, which would open a spot for Walker's return. But the Mariners are also a man short in the bullpen after recalling outfielder Guillermo Heredia and putting reliever Drew Storen on the DL on Monday, so they'll need to add another reliever as well.
Tony Zych and Evan Scribner, two right-handers on the 60-day DL, have both been pitching well recently in rehabs with Tacoma and could be candidates either now or when rosters are expanded Sept. 1. The Mariners do have an open spot on their 40-man roster, so either could be activated without having to make a 40-man move.
Servais did say left-hander Ariel Miranda will likely remain in the rotation after pitching well Sunday in his third start since being acquired from the Orioles for Wade Miley. That would indicate Wade LeBlanc, who is 3-0 with a 4.72 ERA in nine outings (eight starts) could be headed to the bullpen.
"I thought he threw the ball really well," Servais said of Miranda's 5 2/3 innings with three runs and four hits against the Brewers. "As far as deciding when that turn comes up again, is it him or do we keep Wade LeBlanc in there? I like where Miranda is at. Yesterday he was really cruising for five innings.
"We haven't extended him pitch count-wise. He's been in that 80-90 range. But I thought he was throwing the ball really well. He'll certainly be with us and I would look for him to make some more starts."
• Former starter Nathan Karns, on the 15-day DL since July 30 with a back issue, still is not throwing yet and said he's awaiting medical orders before being cleared to resume baseball activity.