Doug Fister felt something in his groin while he was three pitches into his warm up for Sunday's start.

Now, it's unclear if he'll make his next start.

"You know, I can’t guess that. It’s tight today, so we’re treating it as we need to, and we’re going to kind of play it by ear. ... It’s still in one of those stages where it’s still tight, but I haven’t tried to stress it at all yet, so we’re just trying to take it slow," said Fister, who's already spent two stints on the disabled list with an unrelated injury, a pulled muscle in his side.

"It’s just another negative, and we’ve gotta stay positive."

Fister had an MRI, and will test the groin — which has felt about the same since he initially noticed the discomfort Sunday — when he throws his normal between-start side session.

"Oh, yeah. We’ll go out there, play catch, even get off the mound, go as far as we feel it can, and just play it by ear," Fister said. "It’s still in one of those stages where it’s still tight, but I haven’t tried to stress it at all yet, so we’re just trying to take it slow."

If everything pans out, Fister is scheduled to pitch Saturday's game against the Los Angeles Angels of Anaheim. If not, the Tigers may need a minor-leaguer to make a spot start. Drew Smyly, the most logical candidate, last pitched for the Mud Hens on Aug. 17, and is due to make Wednesday's start at Columbus. [Updated: Smyly started the second game of Tuesday's double header vs. Columbus, but threw just one inning, leaving him available for the start Saturday, if needed. ]

Despite the discomfort, Fister went ahead with Sunday's start, but it was pretty obvious to anyone watching that the 3 2/3-inning stint — in which he gave up seven as earned runs, as many as he'd given up in his previous five starts combined — was abnormal.

"He was just out of whack. He wasn't good. He just struggled pretty much. You could see he wasn't quite right. Just one of those days," manager Jim Leyland said afterward, admitting that, given Fister's injury history this year, it was a concern right off the bat. "Yeah, sure. But we’ll just have to wait and see what goes on. His side’s alright. Nothing wrong with his side at all."

But there were signs of something more serious than just "lack of execution," whether it be walking the No. 9 hitter, or matching his season high in walks, or even just the facial expressions of all involved after the game Sunday.

"Right before first inning, I felt it a little. Didn’t get any worse throughout the game, it was just a matter of tight and sore, but nothing that was alarming at the time. ... It’s just on of those things where you don’t really think about it, you just try to go through whatever you have to do to go through, and to pitch," said Fister, noting that he thought the strain, on his right leg, was "nothing too major."

"It doesn’t effect pitching off the rubber at all. That was the thing, why I was able to continue to pitch, and be able to get through it."

Fister tried his best not to let on that anything was amiss.

"He said he was alright, obviously. We checked in in the second inning and he was alright. That’s one of those Catch-22s, you know? So, we’ll just to wait and see how that plays out," Leyland said Tuesday, quickly ending speculation about Fister's availability for his next start. "I would assume so, but we’re wasting time right now. Fister has a groin issue. We will have a pitcher whether it’ll be Fister or somebody else for the next start. Period."