BOSTON — Kevin Garnett took a behind-the-back pass from Paul Pierce, slammed in the dunk to make the lead three dozen points and then slashed his hand across his throat to signal what the Atlanta Hawks already knew.

"It's over," he told the crowd.

The game. The series. The surprising little scare Atlanta put into the NBA's best.

Garnett had 18 points and 11 rebounds, Pierce scored 22 points, and the Celtics turned back the pesky Hawks with a 99-65 victory yesterday in Game 7 of their playoff series to advance to the second round.

Next up: LeBron James and the Cleveland Cavaliers. Game 1 is tomorrow.

"They're a group that's defending Eastern Conference champs," Garnett said. "To do anything, you've got to go through them. It's good that we have home-court advantage. I think it should be a good series."

The Celtics started the celebration early, holding the Hawks to 10 points in the second quarter and doubling their 18-point halftime lead in the third.

The fans yelled: "We want Cleveland!"

"I wish we could have played all of our games in Atlanta," said coach Mike Woodson, whose team won all three home games but never came close to stealing one in Boston. "Nobody thought we had an opportunity to even win a game in this series. We battled them right to the end. We just didn't have it today."

Rajon Rondo, who missed a potential game-tying 3-pointer in the Game 6 loss that forced the series back to Boston, had 10 points and six assists. Kendrick Perkins had 10 points and 10 rebounds before joining the rest of the starters on the bench in the formality of a fourth quarter, just like the Celtics did for much of the regular season.

Boston went 66-16 for the league's best record — 29 games better than the young Hawks team that earned the last playoff spot in the Eastern Conference. The home-court advantage proved pivotal against an upstart team that fed off its own crowd but wilted on the road, losing four times by a total of 101 points.

"I really had no doubt in my mind how we were going to come out," Pierce said. "You kind of saw it from the guys after Game 6 on the plane, there wasn't a lot of talking. We knew that we let a couple of games get away in Atlanta and I knew we were just going to take care of business."

The skirmishes of the first six games boiled over with 9:09 left in the third quarter, with Boston already leading 51-28, when Rondo got the ball on a breakaway in the third quarter and had only Marvin Williams to beat.

The Hawks forward put an arm across his chest and took Rondo to the floor, where he lay for a few minutes while Celtics coaches and teammates checked on him. The officials immediately signaled a flagrant 2 foul and, after reviewing the play, threw Williams out of the game.

"I saw it on TV and it did look pretty bad, so I can't argue that at all. I just want Rondo to know that I would never try to hurt him," Williams said.

Boston coach Doc Rivers vouched for Williams. "Two good kids playing hard," he said.