(Photo credit: Joe Nicholson-Imagn Images)

Seattle Mariners All-Star pitcher Bryan Woo, who has been sidelined the past two weeks with pectoral inflammation, was left off the team's roster for its American League Division Series against the Detroit Tigers.

Woo, 25, left his start vs. Houston on Sept. 19 while warming up for his sixth inning of work. He threw his first bullpen session on Thursday but was limited to 15 pitches at 80 percent to 90 percent intensity, per The Seattle Times.

'Obviously, you don't want to take huge, huge jumps (in intensity),' Woo said after his bullpen. 'You've got to be smart with it. Hopefully we just keep progressing like we have been.'

There remains optimism that Woo will be able to pitch in the next round should Seattle win the best-of-five ALDS. That would be notable for the Mariners considering Woo's consistency this season. The right-hander has a 15-7 record and 2.94 ERA, throwing six-plus innings in 27 of his 30 starts.

Without Woo, Seattle is starting right-hander George Kirby (10-8, 4.21 ERA) in Game 1 on Saturday and will start Luis Castillo (11-8, 3.54) in Game 2 before the series moves to Detroit.

The Mariners included first baseman Josh Naylor on the roster, even though he could need to leave the team during the series. He and his wife, Chantel Collado, are expecting their first child imminently, and the plan is for Naylor to fly to Arizona when she goes into labor.

She remained at their home in Arizona after he was traded to Seattle by the Diamondbacks in July. His acquisition was key to the Mariners' run to the postseason, providing an upgrade at first base by hitting .299 with nine home runs, driving in 33 runs and adding an unexpected 19 stolen bases.

Given Naylor's situation, the Mariners included rookie Ben Williamson on the ALDS roster. Third baseman Eugenio Suarez could move to first base if Naylor departs for paternity leave, and Williamson could take over at third base,

Williamson split the season between Seattle and Triple-A Tacoma. With the Mariners, he hit .253 with 70 hits, one home run and 21 RBIs in 85 games. He posted a .985 fielding percentage at third base.

--Field Level Media