Right-hander John Lackey was placed on the 15-day disabled list by the Boston Red Sox, who recalled right-handed pitcher Alex Wilson from Triple-A to fill Lackey's roster spot.
Lackey was diagnosed with a right biceps strain, but the Red Sox said there is no structure damage to his arm.
Lackey, who had not pitched since Sept. 2011, left Saturday's game against the Toronto Blue Jays in the fifth inning after hurting his right arm while delivering a pitch.
The 34-year-old was coming back from Tommy John surgery. It was feared that he may have re-injured his elbow, but an MRI revealed no damage.
It is not clear how long Lackey will be out. Alfredo Aceves, who relieved Lackey, is the top candidate to fill his spot in the rotation and is the probable starter Thursday and Felix Doubront getting an extra rest day before starting Friday.
Wilson was a second-round pick in 2009. He pitched 72 2/3 innings in relief at Pawtucket last season but hasn't yet made his Major League debut.