CHICAGO – The sight of Tigers' head athletic trainer at the dugout stairs wasn’t good news as Spencer Turnbull walked off the mound at the end of the fourth inning Friday night. Turnbull had won a 12-pitch battle with White Sox slugger Yermín Mercedes, but something wasn’t right.

Shortly after Turnbull got down the dugout steps, Kyle Funkhouser got up to warm in the bullpen. With Turnbull’s early exit with right forearm tightness, the Tigers are back to waiting for good news on an injured starting pitcher.

“It’s muscle in nature, which is a good sign,” manager A.J. Hinch said after Detroit’s 9-8 loss. “The initial diagnosis is positive. Obviously anytime an arm injury or arm soreness comes up in the middle of a game, you hate to hear that, but we’ll see. We’ve got to get him evaluated. He’s got to run the battery of tests. We’ll see where it takes us.”

Turnbull, one of Detroit’s most effective starters for the past month – including his no-hitter two weeks ago in Seattle – had allowed only a Yasmani Grandal second-inning solo homer and Nick Madrigal third-inning infield single through four innings. The battle with Mercedes to end the fourth inning was Turnbull’s final batter of the night.

“He fought to stay in the game,” Hinch said. “I mean, this wasn’t something that we immediately read alarm. There was some soreness in the forearm. Every time you hear that, it’s my job to protect the player from himself, and we took him out of the game. He needs to get evaluated. The initial diagnosis is muscle in nature. That doesn’t make it easy for him over the next five, 10, 15 days, whatever the diagnosis is, but it was enough to get him out of the game.”

Turnbull’s four- and two-seam fastballs were averaging around 95 mph, slightly above his season average according to Statcast. He threw eight fastballs at 95-97 mph in that battle with Mercedes, including a 95.5 mph heater on his 56th and final pitch of the evening.

“I was on the steps of the dugout, about to go out there for the fifth, and I realized Spencer wasn’t coming with me,” catcher Eric Haase said. “And [I was] just kind of shocked at that point. … He really started to hit his stride. He’s making really good pitches to a really tough lineup.”

The Tigers are already down two starters in their rotation, though José Ureña is on track to return Sunday after a right forearm strain near his wrist forced him to miss a start. Julio Teheran hasn’t pitched since April 3 this season due to a right shoulder strain.

Though injuries slowed Turnbull’s rise up the Tigers' farm system early in his pro career after Detroit drafted him in 2014, he has been fairly durable in his brief big league career. He had minimal stays on the injured list in 2019 with right shoulder fatigue and an upper back strain.