Leiter (ankle) reported biceps soreness after the first inning of his latest rehab start at Triple-A Round Rock on Wednesday, Zach Sweet of MLB.com reports.
The Rangers will shut Leiter down from throwing for a few days before reevaluating him, at which point they'll know more regarding the severity of his injury. Manager Skip Schumaker said Friday that Leiter's setback will make it harder for him to return this season as a starter, but he may still have time to return as a reliever if his injury isn't serious.