Woo (shoulder) completed a successful bullpen session Sunday, Daniel Kramer of MLB.com reports.
Woo last pitched Aug. 16 against the Astros, exiting the contest after having tossed six innings of two-run ball while throwing 75 total pitches. The right-hander was lifted due to right shoulder soreness, and his next turn in the rotation was skipped. Woo left Sunday's bullpen session feeling optimistic about the shoulder, and he outlined that he doesn't think that his season is in jeopardy, but he still wants to be cautious. Woo is currently occupying a spot on the 26-man roster, and if he can't pitch in the near future, he will need to be placed on the injured list. The Mariners are expected to make a decision about the 26-year-old's future before the team's series opener against the Phillies on Monday.