BOSTON (AP) -- Kevin Garnett took a moment to control his emotions before running into the arena for his first playoff game in four years.
"I had to slow down as I ran through the tunnel and to hear the crowd, to hear the building rocking and the bleachers were shaking," Garnett said. "I had to take a minute for myself, man, just thank the lord I was back in this position."
He's the biggest reason the Celtics are back in the playoffs for the first time in three years, leading them with his intensity and his skill. Both were there Sunday night when Boston beat the Atlanta Hawks 104-81.
When Garnett left the court for the last time with 3:26 left, fans chanted, "MVP, MVP," an award he won once in his previous 12 seasons, all with Minnesota.
He scored 16 points with 10 rebounds and Ray Allen had 18 points as the two newcomers who led the Celtics to the NBA's best record did what was expected against a team that had 29 fewer wins.
Joe Johnson, who had 19 points for Atlanta but missed 15 of his 22 shots, didn't think it would be this bad.
"I didn't expect it to be like this, but I'm glad we got it out of the way," he said. His teammates, now have "the playoff experience and they pretty much know how it's going to be. Game 2 I expect pretty much a different reaction."
The second game of the best-of-seven series will be in Boston on Wednesday night.
Celtics coach Doc Rivers actually thinks his team can make substantial improvement.
"We'll take the win, but we did some things I know we can do better on both ends of the floor," he said.
They didn't dominate the offensive boards and they couldn't pull away when they had chances in the first half because they let the Hawks drive to the basket.
"Kevin did a good job in the second half communicating and getting the guys where they needed to be so they just couldn't get points in the paint," said Paul Pierce, who had 16 points.
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.
"There were moments when we looked great," Johnson said. "Then again, there were spots where we decided to take it upon ourselves to make a play."
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.
Horford "was unbelievable," Hawks coach Mike Woodson said. "He played like he has been playing playoffs all season."
Garnett had skipped two days of practice for personal reasons before rejoining his teammates Saturday. He didn't miss a beat.
"I'm going to enjoy the ride as long as it goes," he said, "but coming through that tunnel, I was like this is a rush. Some of you guys who have fast cars, it's like sticking your head out of the window going 140."
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.
Being in the playoffs, "is definitely a different feeling from what I've had for a long time," Allen said, "just knowing that we're still playing basketball and there's a lot of people at home watching us play."
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 Rajon Rondo, who landed on the floor after his final basket that made it 73-55 with one quarter left. Rondo finished with 15 points.
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.
"When we make runs to get back in the game we can't let them make another run and go back up 10," Johnson said.
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.
Red Sox owner John Henry sat next to Celtics owner Wyc Grousbeck in the front row. Four of Henry's players, David Ortiz, Mike Lowell, Dustin Pedroia and Kevin Youkilis, sat behind the basket by Atlanta's bench. ... Rivers watched the third period of the Bruins' 5-4 win in which they scored four goals Saturday night to beat Montreal and force a seventh game in their NHL first-round series. "Whether you're a hockey fan or not, that was great sports," he said.