CLEVELAND — They dunked on the Boston Celtics. Then, they danced all over them.

In an unforgettable season like none they've had before, the Cleveland Cavaliers are celebrating each milestone and moment.

LeBron James made five 3-pointers and scored 29 points before swaying to the music in his seat, and the Cavaliers throttled the defending NBA champions, 107-76, yesterday to move within one win of matching the 1985-86 Celtics for the best home record in league history.

At 39-1, the Cavs can tie Boston's hallowed mark against Philadelphia on Wednesday night.

But equaling those Celtics of Bird, McHale and Parrish won't mean anything if the Cavs, who have already clinched the Eastern Conference's No. 1 playoff seed, can't dethrone the current guys in green sometime this spring.

Flexing their defensive muscles, the Cavs led 31-9 after the first quarter, opened a 30-point lead in the second and turned a possible playoff preview into a rout. It was Cleveland's most lopsided win ever in 173 games against the Celtics.

"I looked up at the scoreboard one time and they were shooting 15 percent from the floor," James said. "That's unbelievable."

A message, LeBron?

"Haven't we sent enough messages this year?" he said. "We know we're a good team. It wasn't a message. It was just about getting better."

The Cavaliers, now the 14th team in league history to win 65 games, may have never looked this good.

They outclassed the Celtics, who were missing Kevin Garnett and Leon Powe and have nothing to play for but pride after locking up the East's No. 2 seed.

With Cleveland leading by 26 after three, James was pulled by coach Mike Brown for some of the rest he'll need before making a title run.

When the Cavs reserves pushed the lead to 30, James, Mo Williams and Delonte West boogied together during a timeout as Rick Astley's "Never Gonna Give You Up" pumped through the arena. The trio wasn't shy about things as they mugged for TV cameras to the roaring crowd's delight.

At the other end of the floor, the Celtics sat stoically while watching the Cavs clown around.

"I'm always going to remember that," Ray Allen said. "If I beat a team, as happy as I may be in victory, I'm always going to stay humble and always remember that there's another day. We play each other too much. Those are great motivational thoughts for me."

James insisted the Cavs weren't being irreverent toward the league's most storied franchise.

"We're not trying to disrespect any team or show up any team," he said. "We're all professionals. If you take it as disrespectful, then you got to do something about it."

Daniel Gibson scored 15 and Williams added 13 for Cleveland, which held the Celtics to a season-low in points on 36-percent shooting.

Paul Pierce scored 14 and Glen Davis 12 for the Celtics, who never led and weren't thrilled to rehash the game afterward.

"Does anybody have a Masters update?" coach Doc Rivers quipped. "Let's not talk about basketball."

The Cavaliers have already clinched home-court advantage throughout the playoffs, and with a win today in Indianapolis, they can lock up home court in the finals — if they get that far.

They may have to get past the Celtics, who beat them in a seven-game semifinal series last year, and figure to be their stiffest competition again.

Home court has been vital in the budding Celtics-Cavaliers rivalry: The home team has won 15 consecutive games, including all seven in last year's playoffs.

Although his club was down by 22 early in the second yesterday, Rivers was convinced the Celtics could come back.

"You play together, we'll score," he shouted. "Keep playing."

Trouble was, the Cavs never stopped.