BALTIMORE (AP) — If the Oakland Athletics are to advance in October, they’ll have to do it without Sean Manaea.

Manaea, who threw a no-hitter against Boston earlier this season, joined Oakland’s list of pitchers lost to season-ending surgery when the team announced Tuesday that the lefty was done for the year because of shoulder trouble.

The playoff-contending A’s said Manaea, on the disabled list since Aug. 26, will have an operation to repair a left shoulder impingement on Sept. 19 at the Cedars-Sinai Kerlan-Jobe Institute in Los Angeles.

“He was that guy that every series, when teams played us, they’re looking to see if Manaea’s pitching in the series,” manager Bob Melvin said before a game at Baltimore. “That’s what your top guy means to you. Again, I feel worse for him. We’ll find a way to manage around it.”

The 26-year-old Manaea went 12-9 with a 3.59 ERA and 108 strikeouts in 160 2/3 innings this year. He pitched a no-hitter at home against the Red Sox on April 21, fanning 10.

The A’s entered the day trailing first-place Houston by three games in the AL West. They also were three games behind the Yankees for the top spot in the wild-card standings.

Oakland has been plagued with season-ending injuries to pitchers. Daniel Gossett, Kendall Graveman, Jharel Cotton and A.J. Puk each have undergone Tommy John surgery this year.

“I think the psychology of it, based on the fact that we’ve had so many this year, it’s almost like we’re numb to it,” Melvin said. “It started in spring training with a couple of guys.”

“Everybody feels for (Manaea) and then you just kind of move past it and continue to try to play in the fashion we have. And he’s been out a little bit, too. It’s not like this is a sudden thing that’s happened the last day or two,” he said.