A detailed MRI has revealed that Alex Cobb has a partial tear in his elbow ligament, according to sources.
Cobb will try to pitch through the injury after a program of rest and treatment, but will face Tommy John surgery if that doesn't work.
The Tampa Bay Rays right-hander has already received a platelet rich plasma injection.
Matt Silverman said the team was still in "a wait-and-see mode'' and it was "premature" to speculate about surgery. "He has had some tests performed and we're awaiting results,'' Silverman said.