Tampa Bay Rays right-hander Tyler Glasnow has a partially torn ulnar collateral ligament and a flexor tendon strain, the team said Tuesday after he underwent an MRI.
The Rays said a timeline for Glasnow's possible return would be determined after he undergoes further medical examination.
Glasnow said he won't have surgery for now, and instead will try to strengthen the area. He plans to see another doctor on Friday.
If Glasnow chose to undergo Tommy John surgery, that would sideline this season and could prevent him from pitching next year, too.
Glasnow, 27, was placed on the 10-day injured list, and outfielder Mike Brosseau was recalled from Triple-A Durham.