The Mariners will begin their playoff push against the Detroit Tigers without their young ace.

Bryan Woo, out for the past two weeks with pectoral inflammation, was left off the Mariners’ 26-man roster for the American League Division Series.

The Mariners host the Tigers for Games 1 and 2 this weekend at T-Mobile Park.

“Obviously a tough decision and one that we weighed very carefully, but we just felt like he had made strides as we had hoped and got to a place, but it just looked like it wasn’t going to be able to be in this series,” M’s manager Dan Wilson said before Game 1 on Saturday. “So I think doing the more cautious thing and making sure he gets healthy to where he needs to be. So that was kind of what went into the decision.”

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Seattle Mariners starting pitcher George Kirby gets high-fives from his teammates after getting out of a two men on jam during the sixth inning Saturday, Sept. 20, 2025 in Houston. 231196 231196

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Woo, a first-time All-Star this summer, emerged as one of the premier pitchers in the AL this season, going 15-7 with a 2.94 ERA over 30 starts in a career-high 186.2 innings. He struck out 198, walked 36 and had a 0.927 WHIP.

Woo’s 3.21 career ERA as the best in franchise history for a pitcher with at least 70 starts.

Woo will not be eligible to pitch until the AL Championship Series next week, should the Mariners advance past the ALDS.

The club is optimistic Woo will be available in the ALCS if they do advance.

“He’s continuing to progress as we had hoped, and we talked about that up until this point it’s gone pretty smoothly. No setbacks,” Wilson said. “I think as long as that continues, I think we’ll probably be in good shape at some point in the ALCS. And that’s the hope at this point.”

Woo also struck a hopeful tone in an interview Thursday, after he threw off a mound for the first time since exiting his Sept. 19 start in Houston after five shutout innings.

Woo said the issue now isn’t as much about his pectoral muscle but more about building back arm strength to handle a starter’s workload.

During his work off the mound Thursday, Woo threw 15 pitches at roughly 80-90% intensity. The plan is for him to gradually build up toward 100% over the next week.

“Obviously, you don’t want to take huge, huge jumps [with intensity]. You’ve got to be smart with it,” Woo said. “Hopefully we just keep progressing like we have been.”

Without Woo, the Mariners named George Kirby and Luis Castillo the starters for Saturday’s Games 1 and Sunday’s Game 2, respectively.

Logan Gilbert is expected to start Game 3 in Detroit on Tuesday. Bryce Miller could be in line to start Game 4, though the Mariners have not finalized those plans yet.

“My job, it’s just control what I can control every day,” Woo said Thursday. “I’ll do my stuff from when I get to the field early get everything done before the game starts. And then I have all the faith in the world with all of our pitchers — starters, relievers, whoever it is. They’re more than capable than doing the job like they have been all year.”

Wilson was reluctant to reveal any pitching plans for the M’s beyond Games 1 and 2 other than noting that the original hope was to have Miller available to throw out the bullpen.

“We’ll just have to kind of weigh that versus whether or not he’s going to have to start down the line. So we’ll keep looking at it and keep watching it as we go,” Wilson said.

Tim Booth: Tim Booth is a sports reporter at The Seattle Times, where he covers the Kraken and the ongoing story surrounding possible NBA expansion and helps with coverage of the Seahawks and Mariners.

Adam Jude: ajude@seattletimes.com: Adam Jude is a Seattle Mariners beat writer at The Seattle Times. He previously covered UW Huskies football and the Seattle Seahawks for The Seattle Times.