Boston’s Big Three still has some life in those old bones.

Thirty-somethings Paul Pierce, Kevin Garnett and Ray Allen led the Celtics to their most recent NBA championship in 2008, and this could be their last hurrah together in Beantown.

If so, they’re clearly looking to go out with a bang.

“They have pride,” Atlanta Hawks center Al Horford said Monday. “That goes a long way.”

The Big Three (plus, let’s not forget, Rajon Rondo) have led the Celtics to a 3-1 lead over the Hawks. Game 5 is tonight in Atlanta, with Boston looking to wrap up the series after a 22-point blowout that wasn’t really that close.

The Hawks know what they’re up against, facing an experienced team with a trio of aging stars who clearly have something to prove.

“They’ve got guys who’ve been in wars, who’ve been in the trenches, who’ve been in these type of situations more than we have,” Atlanta coach Larry Drew said. “When you look at their history over the last few years with Paul and KJ and Ray, and now with the way Rondo has been playing, they’ve always been a dangerous team to me.”

Plenty of skeptics figured Boston was all washed up early in the season, and it’s easy to see why. The Celtics approached the midway point at 15-17, closer to missing the playoffs than making any noise in the postseason.

But they were one of the best teams in the league the rest of the way, winning 24 of their last 34 games and carrying that momentum into the playoffs. After three tight games with Atlanta, they took control of the series with a 101-79 rout Sunday night.

The 34-year-old Pierce scored 24 points in less than 19 minutes — not bad, considering he hurt his left knee in the morning shootaround and the Celtics weren’t even sure he’d be able to play. He’s averaging a series-leading 23.3 points a game, including a gutsy 36-point effort in Game 2, when Boston grabbed a win on the road even with Rondo serving a suspension for bumping a referee.

The 35-year-old Garnett and 36-year-old Allen are doing their part, too.

KG is averaging 17 points in the series and leads the Celtics in rebounding (10.5 a game). Allen, who had not played since April 10 because of bone spurs in his right ankle, returned for the past two games in Boston to provide valuable minutes off the bench. He’s averaging 12.5 points.

“I feel surprisingly great,” Allen said.

Of course, the Big Three is actually the Big Four. Rondo got off to a rough start in the series, bumping an official while complaining about a call in the final minute of Atlanta’s Game 1 victory.

After sitting out Game 2, Rondo returned to put up a triple-double (17 points, 14 rebounds, 12 assists) in the next game, allowing the Celtics to pull out an overtime victory after the Hawks rallied from 11 points down in the fourth quarter. He followed with 20 points and 16 assists Sunday night