Shaquille O'Neal out for Game 5

MIAMI -- Boston Celtics coach Doc Rivers said center Shaquille O'Neal was ruled out for Wednesday's Game 5 due to lingering soreness in his right Achilles and calf and sounded pessimistic for his chances to get back on the court moving forward.

O'Neal played only 3½ minutes in the first half of Monday's Game 4 loss and did not return to the court.

"It was physical [in Game 4]," Rivers said before the team's shootaround Wednesday morning at American Airlines Arena. "I don't know yet [about Wednesday's Game 5]. I would say I doubt it. But we'll see. [O'Neal played] a little stretch [in Game 4], then it got worse."

Rivers sounded glum about O'Neal's potential to have an on-court impact moving forward.

"There's nothing he can do," said Rivers. "It's not like he's not trying. I told our team that [Tuesday], he's done everything possibly he can do to get healthy. Unfortunately for him, he hasn't been able to do it.

"When he was originally injured, no one even thought it was that serious. I don't know what I said, because I talk to you guys every day, but I think I was saying it's not even a big deal, he'll be back in four or five days. It just never healed. It still hasn't and now every time he plays it gets worse. So, there's nothing you can do about it."

Meanwhile, Rajon Rondo was set to start for the Celtics. He's been receiving treatment on a dislocated elbow.

"[The elbow is] not much better, I can tell you that," said Rivers before the game. "In some ways, I think he's actually in more pain than going into Game 4. But I think he at least has an idea on how to deal with it more. We're hoping that he can give us something and, if he can't, we'll have to make a decision on the floor."

Rivers didn't want to speculate too much on O'Neal's future and whether this could be his final NBA days.

"I think it's too early to even talk about it," Rivers said. "I've learned personally, you never try to make any decision during the heat of the battle. Emotionally, you're always going to make the wrong choice. I think he'll walk away for a bit this summer, then decide what he wants to do.

"I just know that this has been emotionally draining for him. More than you guys, perhaps, would know. He feels awful about this. This is why he came here, to get to the playoffs and play in the playoffs. Not being able to do that, has really hurt him."

Rivers admitted it's tough for older players.

"It's hard, especially when you know him," Rivers said, "with any of those guys that are getting older. I had Patrick Ewing in his last year in Orlando and I played with him. I'm the coach telling him he's not going to play anymore. I don't know, that's an awful position. What makes them great is their pride. Even when they're barely walking, in their minds, they still think, 'I can change the outcome of the game.' Sometimes you have to be the one to tell them they can't and that's very difficult."

O'Neal appeared in 37 games for the Celtics during the regular season, but played only 5½ regular-season minutes after Feb. 1. He returned for 8½ minutes in Saturday's Game 3 win in Boston, but the injury hasn't responded well to the activity since then.

Chris Forsberg covers the Celtics for ESPNBoston.com.