Boston Red Sox right-hander John Lackey re-injured his right arm 17 months after undergoing reconstructive surgery in Saturday's start against the Toronto Blue Jays.

Lackey clutched his arm in agony after throwing a pitch in the dirt to Toronto's Jose Reyes.

He is flying back to Boston Sunday morning for an MRI on what the Red Sox are initially calling a right biceps strain.

"The testing he went through in the training room after some time elapsed, the test strengths, the manual testing in here showed good strength, almost full strength," Red Sox manager John Farrell said. "So there are some initial positive signs here, but we can't rule anything out and that's why the exam will take place."