PHILADELPHIA (AP) Kevin Garnett turns 36 on Saturday, a youthful age for any man, except for the rare ones with nearly 55,000 punishing minutes absorbed on an NBA floor.

Garnett knows all the ageist labels attached to the Boston Celtics. How they're called The Over The Hill Gang, and the wisecracks about flashing AARP cards before they check into a game, and how each crucial postseason game raises questions about The Big Three's last hurrah.

The Celtics have known since training camp a championship run centered around Garnett, 36-year-old Ray Allen, and 34-year-old Paul Pierce was on its last legs.

Aging legs, yes.

But far from finished.

Garnett displayed dominant proof in Boston's Game 3 rout against the Philadelphia 76ers. He scored 27 points and grabbed 13 rebounds to help the Celtics snare a 2-1 lead in the Eastern Conference semifinals.

The Sixers under-25 crew had no way to slow down Garnett.

He made 12 of 17 shots in Game 3 and is shooting 63 percent overall in the series.

Let others get nostalgic for the stretch run of Boston's terrific trio. Garnett only cares about winning the next game, the next series, and another championship to pair with the one The Big Three clinched in 2008.

''I'm focused on the playoffs,'' Garnett said Thursday. ''I haven't given much thought to it. I'm definitely aware of it. We know what the possibilities are. But at this point, right now, it's the playoffs.''

Garnett heard a few screams of ''We love you, Kevin!'' from passing fans as he answered questions alongside Pierce outside the Four Seasons Hotel.

The chants should be more antagonistic in Game 4 Friday in Philadelphia.

Garnett will tune them out the way he's zoned out the light attempts at defense the Sixers have thrown at him. Even at 35 (or 36), Garnett is still more mobile than Philadelphia's frontcourt combo of Spencer Hawes and Elton Brand. Lavoy Allen's foul troubles have limited his guarding Garnett.

''You have to do a better job early,'' Sixers coach Doug Collins said. ''You can't let him get such deep position. You can't let him run underneath the rim, turn and face the basket. You have to meet him at the free throw line.''

Pierce was slowed by an MCL injury in his left knee, until a gutsy 24-point, 12-rebound outing in Game 3. Allen scored only three points and has been secure enough in letting Garnett, Pierce and Rajon Rondo handle the scoring load that he turned down KG's offer to get him more touches.

Garnett told Allen: ''We've got to do whatever we can to get you open.''

''I looked at him and said, 'Kevin, you're the guy getting shots. You're the guy that's scoring. We just won by 20. I don't need to, for the sake of my ego, do anything like that. We just keep doing what we're doing. If they keep guarding us this way, then you've got to keep doing what you're doing.'''

Garnett and Allen are free agents at the end of the season. A championship run that seemed blocked by young-gun All-Stars eased up with Chicago out of the picture. The Miami Heat are without Chris Bosh indefinitely. And the Sixers showed in Game 3 how vulnerable they are when a top team is clicking.

Pierce realizes the sense of urgency to win a championship with the trio playing their final games together. They want to make it last.

''We've realized that from Day 1. I think pretty much the last couple of years we've been feeling like that,'' Pierce said. ''But the influence is to try and win another championship, regardless of if this is going to be our last time together. Who knows what the future is going to hold for all of us?''

The Sixers, meanwhile, are trying to find a way to slow down the old guys.

They looked totally lost after the first quarter. The Sixers weren't hitting shots and the defense couldn't bail them out with key stops. Starters Brand, Hawes and Evan Turner combined for only 11 points.

''It was a little embarrassing because you don't want to put on a showing like that, and definitely at home,'' guard Jrue Holiday said. ''At the same time, it's motivation to not do it again.''

Collins showed the Sixers game film from the first half on Thursday and the reviews weren't pretty. What they saw was a team that never had a grip on their defensive assignments. The Sixers offered little resistance once Garnett got hot in the second quarter (13 points) with a flurry of 10- to 16-foot fadeaways and open jumpers.

''I never considered them old,'' Collins said. ''They sure looked pretty young to me. Garnett's playing great.''

Just how the Celtics like it.

''I don't know if I'm surprised. It's in him,'' coach Doc Rivers said. ''He's feeling pretty good. he's at a great place mentally. That's always nice. I think our guys understand how important he is to our team. He understands that as well. It's just great. I'm happy for him.''