Shaquille O'Neal has to take day off

At his advanced NBA age, Shaquille O'Neal is slowly coming to grips with his body's inability to bounce back from injury. That doesn't mean he's accepting the limitations.

With the area around his right knee still tender from a late-October collision with New York's Amare Stoudemire, O'Neal asked the Boston Celtics medical staff to administer a pain-killer that would allow him to play in Thursday's tilt against the Philadelphia 76ers.

When they refused, with his long-term health in mind, Shaq, 38, reluctantly had to accept sitting out his sixth game of the season after being limited in the past two.

O'Neal knows the goal is to win down the road, and that means swallowing some of his toughness after 18 seasons in the league.

"I never thought this day would come," O'Neal admitted before Thursday's game. "Especially for me. When I was young, I thought I could play through anything. ... I could get stabbed, go to the hospital, and come back ready to play. Sometimes nick-knack injuries don't go away.

"The thing about this team, this staff, they don't want you to rush back. I'm from the old school, so I'm like, 'Shoot it up,' give me some drugs. But the focus is on 1825."

That year references is Shaq shorthand for winning another title this season, which would mean 18 world titles for Boston; 2 for the Big Three and coach Doc Rivers; and 5 for O'Neal's cumulative total.

With 1825 in mind, the Celtics have exercised extreme caution with injuries, even when it has left them shorthanded as it did Thursday when, playing without both O'Neals -- Shaq and Jermaine -- for the first time this season, Boston leaned on rookie Semih Erden in a starting role.

Although Shaq expressed hope that he might be able to return to the lineup Saturday in Charlotte, it's clear the Celtics will not rush him.

"We want him to be healthy, it's very important for him to be healthy," Rivers said. "We want him to play as many minutes as he can, we need him to, for a lot of reasons, because we have J.O. and [Kendrick Perkins] out, but at the end of the day, we need him healthy. So we're not going to do anything that possibly could take him out for the long haul.

"I don't know what line to walk with Shaq. He's 38 years old, he has a lot of mileage, and we want to keep him in playing shape, and in rhythm with our offense and defense, so he knows our schemes. It's a fine line to walk and I have no idea if we're walking it right or not, and so we're going to listen to him and [team trainer] Eddie [Lacerte]. That's what I'm going by, Eddie is the guy -- he'll say, 'Maybe we should give him this day off' -- then that's how we'll do it."

O'Neal is averaging 11.2 points and 6.4 rebounds in 22 minutes per game in 16 appearances this season. For all the consternation about him being a defensive liability, the Celtics clearly missed him at both ends of the court Thursday.

And every time he turns back the clock, like with a 25-point, 11-rebound effort against New Jersey in late November, it's hard to remind O'Neal that he's 38 now.

"It's not easy [to sit out]," O'Neal said. "I only know one way."

Then again, O'Neal knows there's only one way he'll be happy with how this season ends, so he stayed off the court Thursday, hoping he'll be standing on it in June.

Chris Forsberg covers the Celtics for ESPNBoston.com.