Shelby Miller's forearm injury is worse than the Arizona Diamondbacks originally feared.
Miller told reporters Thursday he has a partial tear of his ulnar collateral ligament (UCL) and the 2015 MLB All-Star is considering Tommy John surgery.
He is currently on the 10-day disabled list.
The 26-year-old right-hander left his start against the Los Angeles Dodgers with forearm tightness on Sunday.
Results from an MRI were originally inconclusive, but the scan was sent to noted orthopaedic surgeon James Andrews for a third opinion.
"I still haven't made a decision on what I'm going to do yet," Miller said, via AZCentral.com. "I'm still kind of processing all of it. It's still kind of early."
Miller is 2-2 this season with a 4.09 ERA, a big improvement from last season's nightmare (3-12, 6.15 ERA).