Manaea will have the operation on Sept. 19, the A's announced. The team said further details will be provided upon completion of the surgery, though manager Bob Melvin hinted the southpaw could be sidelined a full year.
"I think the specifics we'll talk about moreso after the surgery so we know exactly what was repaired," Melvin told reporters, "but unfortunately, it's another one we're going to have to wait basically a year for, and we really and truly feel more for him."
Manaea, 26, was placed on the 10-day disabled list with rotator cuff tendinitis on Aug. 26. Prior to the injury, he was 12-9 with a 3.59 ERA in 27 starts this season. He threw a no-hitter against the Boston Red Sox in April.
Donaldson was acquired from the Toronto Blue Jays on Aug. 31 and had played in just 36 big league games this season. He entered the day hitting .234 with five homers and 16 RBIs and hadn't played since May 28.
Meanwhile, the Indians will skip ace right-hander Corey Kluber's next turn as they begin setting up their rotation for the postseason. Manager Terry Francona said Kluber (18-7, 2.91 ERA) is fine physically despite lasting just 1 2/3 innings in Monday's start against the Tampa Bay Rays.
--Astros right-hander Brad Peacock left the team to return to Houston after being diagnosed with hand, foot and mouth disease, manager A.J. Hinch told reporters.
Hinch said Peacock felt ill during a weekend series in Boston and his condition went downhill after the Sunday night game.
Peacock, 30, is the third known major league pitcher to be diagnosed with the disease this season. New York Yankees left-hander J.A. Happ and New York Mets right-hander Noah Syndergaard also contracted the viral disease that is more common in children. Peacock is 2-4 with three saves and a 2.98 ERA in 55 appearances (one start) this season.
--Field Level Media