Gallegos was placed on the 10-day injured list with a right groin strain Friday.
Gallegos suffered the injury Thursday against the Tigers. It's not clear whether or not he'll be able to return for the final week of the season. He'd saved a career-high four games this season while posting a 3.97 ERA and a 0.79 WHIP in 11.1 innings prior to suffering the injury. Andrew Miller could wind up being the primary ninth-inning option in his absence. Nabil Crismatt was recalled in a corresponding move.