BOSTON — Ray Allen scored 18 points and Kevin Garnett had 16 as the two newcomers who led the Boston Celtics to the NBA's best record sparked them to a 104-81 win tonight in their playoff opener against the Atlanta Hawks.

Garnett stopped a 14-3 Hawks run with a jumper, starting a six-point Boston surge that made it 35-27 in the second quarter. And Allen scored 10 straight Celtics points midway through the third that extended a 13-point lead to 67-48 with 5:39 left in the period.

The top-seeded Celtics' lead ranged from 12 to 27 points the rest of the way.

The second game of the best-of-seven series will be in Boston on Wednesday night.

Eighth-seeded Atlanta, which ended the NBA's longest playoff drought with its first appearance in nine years, was led by rookie Al Horford with 20 points and 10 rebounds and Joe Johnson added 19 points.

Garnett had skipped two days of practice for personal reasons before rejoining his teammates Saturday. He didn't miss a beat.

Playing in his first playoff series in four years, the former Minnesota star had 10 rebounds. When he left with 3:26 remaining in the game, fans chanted "MVP, MVP."

Allen is in the playoffs for the first time in three seasons after being obtained in an offseason trade with Seattle to provide a smooth shooting touch. He showed that when he hit his four consecutive shots, two of them 3-pointers.

Paul Pierce scored 16 for Boston and Rajon Rondo had 15.

The Celtics are 4-0 this season against the Hawks with all the wins by at least 10 points.

They pulled away in the third quarter behind their starting backcourt. They led 57-44 with eight minutes left in the period, before Allen's shooting spree preceded six straight Boston points by Rondo, who landed on the floor after his final basket that made it 73-55 with one quarter left.

The Celtics led 26-13 with three minutes left in the first before the Hawks made it 29-27 on Marvin Williams' jumper with 10:39 left in the second. By that time, Atlanta's Josh Smith, second in the NBA with 2.8 blocks, already had three.

Then Garnett, on Boston's bench with two fouls, returned and immediately hit a 14-footer to kick off the 6-0 run.

With the score 35-31, Sam Cassell scored the game's next seven points, giving the Celtics a 42-31 lead with 5:11 left in the second.