Shaquille O'Neal's calf injury has shown "some improvement," according to Boston Celtics coach Doc Rivers, and the big man hasn't been ruled out for Sunday's Game 4 against the Knicks.

O'Neal has played only 5½ minutes since Feb. 1 with Achilles and calf injuries.

"He's going to try to [get on the court Thursday]," Rivers said. "I just don't see it. I'm just going to be a real doctor right now and say I doubt it. He's going to try to do something [Thursday] and we'll see.

"He's had some improvement, but I don't know how much. I'm just going by what [team trainer] Eddie [Lacerte] and [team physician Dr. Brian] McKeon tell me. They thought he's had some improvement."