At the end of a week that had been dominated by the storyline of their big, aging veterans going down with injuries, the Celtics got a reminder that their biggest, aging-est veteran of all was still healthy and going strong.

The Celtics have taken nothing for granted this season with Shaquille O'Neal, whose hip, knee and calf ailments have made his health a constant concern this season. Coach Doc Rivers said before Friday night's game that Shaq was always considered day-to-day, and when asked for an explanation, he offered only that the 38-year-old big man was "old as hell."

But then O'Neal, thrust into a bigger role than ever by necessity on Friday night, stepped up and played a season-high 35 minutes against the Bobcats. He made the most of them, finishing with 23 points on 10-of-12 shooting, five rebounds, five blocks and two assists. He even made all three of his free throws.

Kevin Garnett and Jermaine O'Neal might have been injured, and Semih Erden might have been in foul trouble. But no matter -- Big Diesel was there to fuel the Celtics to a 99-94 victory on their home floor.

"His energy was the difference," said Rivers, doing a complete 180 from his pregame "old as hell" wisecrack. "It was huge. Without Shaq tonight, we're not happy right now."

O'Neal didn't arrive in Boston expecting to have many nights like this, where he took over the game with his offense and carried the C's to victory. But he's always maintained that he's still got it in him.

"If I get the touches and I get the calls, most the time the outcome is going to be like that," O'Neal said. "But that's not really my role here. I'm here just to do whatever Doc asks me to do."

We all expected that O'Neal would be effective in short bursts this season, good for a quick five-minute jolt of offense here or there. But 35 was entirely unexpected. The Celtics didn't have a choice -- the rookie Erden entered late in the first quarter, he picked up three fouls in a span of less than four minutes, and with 43 seconds to play in the opening quarter, he was back on the bench. Like it or not, Shaq was back in.

Rather than mope about the unexpected minutes, Shaq proceeded to singlehandedly pour in the Celtics' next eight points. Between 2:54 left in the first quarter at 6:05 left in the second, he was the only Celtic who scored.

Shaq ended up with only his second 20-plus-point game in Celtic green, and only his seventh since leaving Phoenix in the summer of 2009.

"I did think there would be a game or two where he'd have the points, and then there'd be a game or two where he'll contribute in other ways," Rivers said. "But we don't go into the game thinking that we're going to get Shaq 15 shots, and all that. We go into the game allowing the game to happen. If it happens where we can get him shots, then we try to."

Here's how you know Shaq understands the Celtic way: He comes through when the team needs him most. He's been willing to lie low all season, setting aside his own ego for the good of the team. But in the Celtics' time of need, with two big men in the training room and another on the bench, he was able to step up.

"I knew that whatever happened, I was going to be ready," O'Neal said. "I've been in foul trouble and I haven't really haven't played a lot of minutes, so there was really no excuse for me to be tired. I came out and got a few more touches tonight, and I just did what I do.