CLEVELAND -- For the first time in 661 days, Danny Salazar took the mound in a big league game. But when his fastball velocity peaked at 88.3 mph, it was clear something wasn’t right.

At the beginning of the Indians’ 7-1 loss to the Astros on Thursday night, Salazar felt mild pain in his groin that never subsided. As he walked to the rubber each inning, the discomfort grew worse, which made it difficult for him to get his legs behind him to increase his velocity.

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“We’re gonna check it out tomorrow and see how bad it is,” Salazar said. “I don’t think it’s something really bad. It happened to me in Arizona, like, two months ago. I didn’t feel it after until today.”

Salazar missed all of 2018 after reporting to Spring Training with a sore right shoulder that eventually needed season-ending surgery in July. In his six rehab starts over the last month, the 29-year-old pitched to a 2.60 ERA and tossed 7 1/3 scoreless frames over his last two outings in Triple-A. In his last rehab start, Indians manager Terry Francona said that Salazar’s velocity sat around 92 mph.

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“Not feeling the way that I wanted to feel out there, coming from having six outings in the Minor Leagues, feeling great -- arms, legs, everything -- and this happening today, it was kind of something that took me down a little bit,” Salazar said. “But I had to battle with it.”

“The one thing, in his rehab starts it seemed like his velocity kept climbing, and obviously it didn’t happen tonight,” said bench coach Brad Mills, who managed Thursday’s game as Francona recovered from minor eye surgery. “And in the fourth inning, he had mentioned to us that his groin was bothering him, and so that’s why we got him out right there.”

Even without blowing up the radar guns, Salazar was able to hold one of baseball’s most difficult lineups to two runs -- two solo homers -- on four hits through four innings. He walked three batters and struck out two. Heading into the start, the Indians knew that Salazar was only stretched out to approximately 70 pitches. Despite his pain, he was able to get close to that target, throwing 66 pitches, 36 for strikes.

“At least I got through four innings, only allowed two runs,” Salazar said. “I’m going to take it as a plus for being out of the games here for two years. … It was a little weird, like it was my first time. It was actually good being back, feeling the adrenaline, seeing my teammates support me out there. All of the fans, too. That was great.”

Mills and Salazar said that the hurler will be re-evaluated when he comes to the ballpark on Friday before the series opener against the Angels. After trading Trevor Bauer to the Reds earlier this week, the Indians have a vacancy in the starting rotation that needs to be filled, and Corey Kluber (fractured right forearm) is still a few weeks away from being in consideration.

If Salazar won’t be able to make another start, it could be likely that the Indians will call on Aaron Civale, who tossed six shutout innings in his only start -- and big league debut -- with Cleveland this season. Civale is ranked by MLB Pipeline as Cleveland's No. 24 prospect.