Hill showed discomfort after walking Adam Dunn in the seventh. Hill was immediately replaced by Daniel Bard, who worked out of the bases-loaded one-out jam without allowing a run.
"Originally, I was just focused on catching the pitch, but then I looked out there and noticed he was clutching the elbow in some pain," said catcher Jarrod Saltalamacchia. "He said he felt something pop in there and just like a burning, so hopefully everything turns out OK. But it's always scary when it's the elbow."
Ulnar collateral ligament injuries can often result in Tommy John surgery, though Bard checked in with Hill after the game and reported optimistic news.
"He said it wasn't structural damage," Bard said. "I think Rich is OK though, from what I heard. He said it was just scar tissue that kind of popped. He seemed OK and said he passed all the tests when they were testing for [a] UCL [injury]."
Hill had yet to allow a run, striking out 12 in eight innings of work this season. Manager Terry Francona said Hill's early test results looked promising.
"On the just examination, the cursory examination, he actually looked OK, which is good," Francona said. "When somebody comes off the mound like that, we've got to get him checked thoroughly, which we will. Hopefully we'll know a little bit more tonight."
If Hill's hurt to the point that he goes on the 15-day disabled list, the Red Sox could turn to fellow southpaw Felix Doubront, who returned to Triple-A Pawtucket from a left groin injury on Monday. Doubront threw 47 pitches (29 strikes) and struck out five batters over 3 1/3 innings, though the initial plan was to stretch him out as a starter. The day after his start, Doubront said he was feeling really good.
Southpaws Andrew Miller and Hideki Okajima could also be options. Miller's been used out of the rotation and has shown command issues, despite racking up a 2.47 ERA. Okajima tossed a scoreless inning of relief on Tuesday and has allowed one run in three innings of work since clearing waivers and returning to Pawtucket.