Indians closer Chris Perez will miss at least one month and possibly six weeks with a strained left side muscle.
Perez had thrown about 30 pitches on Thursday when he pulled up with what he thought was a cramp.
Cleveland trainer Lonnie Soloff said there's still a chance Perez will be ready for Opening Day on April 5, depending on how he does with treatments.
Indians Lose Closer Perez For 4-6 Weeks