The Seattle Mariners are being cautious with All-Star right-handed starting pitcher Bryan Woo, based on an injury update provided by M’s general manager Justin Hollander on Tuesday.

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Woo will not make his not scheduled start on Thursday against Colorado as the Mariners continue to evaluate inflammation in his right pectoral muscle, but there are “zero plans” to place him on the 15-day injured list, Hollander said.

The 25-year-old Woo exited his outing last Friday at Houston after throwing five scoreless innings on 67 pitches. He threw a pair of warm-up pitches ahead of the sixth inning before leaving due to the pec issue.

“He’s doing well,” Hollander said. “He’s not gonna start the game on Thursday, mostly because his routine has been pretty broken up by what’s happened since he walked off the mound the other night.

“We’re still taking it day by day, (but) zero plans to place him on the IL right now.”

Hollander said the inflammation in Woo’s pectoral muscle reacted “great” to treatment, and that he will throw a baseball Wednesday or Thursday.

“It’s already feeling much better,” Hollander said. “He’s in a really good mental place right now. He was very disappointed on Friday postgame just with the uncertainty, and he really wanted to go dominate the entirety of the game, and he was on pace to do that.

“The way he has felt the last couple of days has been very encouraging for him and us.”

Hollander said the team is taking it day by day, but “would anticipate” Woo ramping up again toward the end of the week.

“Whether that means pitching in a game or just throwing sort of a get-after-it bullpen, we’ll see,” Hollander said. “But again, doing really well and don’t really want to go beyond (that).”

Bryan Woo has responded well to treatment but will not make his start Thu. Plan is to throw Wed. or Thu. and go from there. The Mariners are not putting him on the IL because they don’t feel he will need 15 days.

— Shannon Drayer (@shannondrayer) September 23, 2025

The American League West-leading Mariners close the regular season this week with a six-game homestand against the MLB-worst Rockies and the defending World Series champion Los Angeles Dodgers.

Seattle holds a three-game lead over the Astros atop the AL West. The M’s also have a two-game lead over the AL Central-leading Detroit Tigers for the AL’s No. 2 seed, which is significant because the top two seeds receive a bye past the best-of-three AL wild card round and into the best-of-five AL Division Series. Seattle also holds the head-to-head tiebreaker over both Houston and Detroit.

The wild-card round begins next Tuesday, Sept. 30, and the ALDS begins Saturday, Oct. 4. If the Mariners placed Woo on the 15-day IL retroactive to this past Saturday, the earliest he could return would be Oct. 5.

Hollander was asked how much that timeframe factored in to any IL consideration for Woo.

“I just don’t think right now we have any indication that he needs 15 days,” Hollander said. “At this time of the year, we’re not blind to the context of what 15 days means right now. But also, he’s doing really well and we don’t think he’ll need 15 days. So even if we were in June, I don’t think he would be an IL placement right now.”

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