Royals reliever Kelvin Herrera was diagnosed with a "slight" flexor tendon strain in his forearm, a potentially serious injury that could knock him out for the remainder of the series or longer.
Royals Manager Ned Yost said when Herrera underwent an MRI exam, doctors found no damage and very little fluid. Yost called that news "really, really good." He is hopeful Herrera could be back as soon as Game 3 in Kansas City on Sunday.
"Herrera's fine," he said. "We're going to reevalutate it on the off day tomorrow, and hopefully he's going to be available for Sunday, but we'll see."
The injury, though, is often a sign of ulnar-collateral ligament damage. Angels left-hander Tyler Skaggs suffered a flexor tendon strain earlier this season and later underwent Tommy John surgery.
Herrera is the seventh-inning option in the Royals' loaded bullpen. He had a 1.41 earned-run average through 70 regular-season innings. He left the game after one batter Thursday.
The Royals will now pitch by matchups, with righty Jason Frasor and lefties Brandon Finnegan and Tim Collins as the likely options.
Major League Baseball announced start times for Games 4 and 5 of the division series, if necessary. Game 4 would be in Kansas City on Monday at 3 p.m. PDT. A Game 5 in Angel Stadium on Wednesday would begin at 5:30 p.m. if the Detroit-Baltimore series is over or 6 p.m. if there is a Game 5 between the Tigers and Orioles.