So far, the news on John Lackey continues to be as positive as the Red Sox could have hoped.

An MRI administered Sunday revealed inflammation, but "not any detection of a tear," in Lackey's right biceps, according to manager John Farrell. As such, the Sox have not made a decision about whether to place Lackey on the 15-day disabled list, although he's not going to be ready to start on his regular day, which would be Friday against the Tampa Bay Rays.

With a day off tomorrow, however, the Red Sox may not need a fifth starter until at least Sunday against the Rays. If Lackey can't pitch by then, right-hander Alfredo Aceves remains a leading candidate to take his turn in the rotation, Farrell said.

Farrell characterized Lackey as having "improved," but also as still being in a "48- to 72-hour recovery period" after grabbing his right arm and walking off the mound in the fifth inning Saturday in Toronto. Farrell indicated that Lackey will be reexamined today, even after having a full checkup with team orthopedist Dr. Peter Asnis yesterday.

"We'll be cautious with this," Farrell said. "We're not at the point of saying he's (going on the) DL yet either."