BOSTON (NBA.com exclusive) -  --  Supposedly this is an NBA rivalry, but the description never quite seemed to fit the bill, with the Boston Celtics sweeping the season series last year. Tonight, however, the Atlanta Hawks made one heck of a case.

"They kicked our butt," Celtics coach Doc Rivers said.

Drama was hardly absent as the Hawks showed poise and maturity in handing the Celtics their second home loss, 97-86. No, there weren't any cries of "Nothing easy!" from Zaza Pachulia. Nor were there signs of bad blood other than a brief  tête à tête between Pachulia and Kevin Garnett. But the manner in which the Hawks out-worked, out-executed and wore out their opponent now forces the Celtics, and the rest of the league, to take a serious look at the team formerly considered not quite a rival.

"Nobody else believed in us," Joe Johnson said. "We came out and we believed that we could beat this team on the road and we did that."

Entering the game with the second-highest fourth-quarter scoring margin in the league, the Hawks backed up the numbers, out-rebounding the Celtics, 11-6, and forcing five key turnovers in the quarter as Jamal Crawford and Joe Johnson acted like closers, combining for 42 total points.

"When you turn the ball over to an athletic team, you're going to give up points," Rivers said. "When you don't put bodies on athletic guys, you're going to give up points. We did both of those tonight."

And yet they still had a chance.

With the teams combining for 10 first-half free-throw attempts, there was a good chance that the first team to consistently get to the line would carry a huge advantage. Halfway through the third, the Celtics had doubled up Atlanta's attempts and their typical third-quarter run seemed imminent. But the Hawks trumped the Celtics in the fourth, sinking nine freebies while Rajon Rondo and Paul Pierce each had late misses at the line.

The Celtics received a bit of a scare when Paul Pierce (24 points) suffered a bruised knee that sent him to the locker room with 3:15 remaining in the third quarter. He returned with 10:29 to go in the fourth and gave Boston a late four-point flurry, but for every minute he was out, and most that he was in, the Hawks were the better team.

Poor shooting from beyond the arc hampered the Celtics all night, finishing 1-for-15 and dampening the effect of otherwise good shooting. Even worse was their effort on the glass.

Atlanta won the possession game in the first half, outrebounding the Celtics, 25-13, despite Boston's advantage in nearly every other statistical category. Coupled with an aggressive attack -- eight of Atlanta's first 16 points were in the paint and 24 of 41 overall -- the Hawks weren't just sticking around like so many other visitors to TD Garden.

"If you don't bang, get loose balls, and rebound with them, you don't beat this team," Mike Woodson said.

And in the second half, the Hawks were clearly in control, finishing with a 47-29 margin on the boards and 16 offensive rebounds, consistently beating the Celtics to the ball despite fairly standard box-out situations.

"You aren't going to win a game getting outrebounded 47-29," Garnett said. "Rebounding is a group effort and it starts with the bigs."

Tonight, it started with Atlanta. More so than even the Phoenix Suns did one week ago, the Hawks made the Celtics look positively mortal. And in turn, made themselves look like true rivals.

"We needed to beat a good team on the road like this," Woodson said. "We were committed all the way for 48 [minutes]. I hope this is a game that continues to carry our team on to bigger and better things."