He entered Tuesday's game against the White Sox in the ninth and served up an RBI double to Tyler Flowers and a two-run double to Jordan Danks. After throwing two pitches to Alejandro De Aza, Strop was checked by athletic trainer Ed Halbur, then pulled.
"I've been dealing with my groin since five days ago," Strop said. "It's been five days and it's still bothering me real bad and we're going to get an MRI tomorrow and see what's going on in there."
Strop was getting treatment in hopes of not having to go on the disabled list. The team won't know the extent of the injury until the right-hander is examined Wednesday.
"I don't want to go on the [disabled list], I want to help the team," Strop said.
He wanted to pitch on Tuesday.
"If I was right, maybe I could've made my pitches, execute better pitches," Strop said. "I couldn't throw my slider at all. Every time I rotated a little bit, it was bothering me. I was trying to get away with my sinkers, but they were right on it, knowing my slider wasn't working."
Carrie Muskat is a reporter for MLB.com. She writes a blog, Muskat Ramblings, and you can follow her on Twitter @CarrieMuskat. This story was not subject to the approval of Major League Baseball or its clubs.