The Seattle Mariners, who are in pursuit of the first American League pennant in franchise history, received a needed boost Sunday when they announced the return of All-Star right-hander Bryan Woo.

The staff ace has not pitched since leaving a start Sept. 19 with what was later diagnosed as pectoral inflammation. But he was included on the Mariners’ roster for the American League Championship Series ahead of Sunday night’s Game 1 matchup against the Toronto Blue Jays.

After the Mariners outlasted the Detroit Tigers in the American League Division Series, Woo appeared to be nearing a return. Though no roster decision had been officially announced, president of baseball operations Jerry Dipoto said Saturday he expected Woo to appear at some point during the ALCS.

Woo, 25, posted a 2.94 ERA over 186 2/3 regular-season innings. He had tossed five shutout innings before experiencing discomfort in his last start. But even before the ALDS started, Woo was healthy enough to finish off a bullpen session and even pitch a simulated inning. He will likely pitch midway through the series, when it shifts to Seattle for Games 3 through 5.

The Mariners, who are in the ALCS for the first time since 2001, could use the infusion. Winning Friday’s 15-inning thriller over the Tigers required using three starters: George Kirby, who took the ball for the start, and Luis Castillo and Logan Gilbert, who both came on in relief.

Bryce Miller draws the Game 1 assignment for the Mariners in the ALCS starting in Toronto. He’ll be opposed by the Blue Jays’ Kevin Gausman.