BALTIMORE—Two days after he walked off the mound with a back injury, Craig Kimbrel was in the outfield on Tuesday throwing. He later threw in the bullpen. When the Orioles’ closer left Sunday’s game after allowing a walk and a two-run home run in a 7-6 loss to Oakland, there was concern that he might be out for an extended time.

Manager Brandon Hyde said on Monday he hoped Kimbrel would avoid the 15-day injured list, and when the Orioles activated left-handed reliever Cionel Pérez, they optioned Dillon Tate to Norfolk, raising hope that Kimbrel would be able to pitch again soon.

Left-hander Danny Columbe was used as the closer in Monday night’s 2-0 win over the Yankees, which pushed the Orioles percentage points ahead of New York atop the American League East.

“Not really sure,” Hyde said about Kimbrel’s availability for Tuesday night’s game against the Yankees. “He’s going through some treatment stuff right now, and then I’m going to talk to him here in a little bit. As of right now, 3:42, I’m not really sure.”

Note: Hyde said he had defined plans for starting pitchers Kyle Bradish and John Means, who are both still on the 15-day injured list and haven’t pitched for the Orioles this season. Hyde didn’t share those plans. The Orioles haven’t announced a starter for Thursday’s fourth and final game against the Yankees.