ATLANTA -- A month into the season, frustration is building in Boston. The hot-shooting Atlanta Hawks added to the Celtics' discontent.

Atlanta forward Paul Millsap led seven Hawks in double figures with 25 points, and point guard Jeff Teague added 16 points and nine assists in a 121-97 win over the Celtics on Tuesday.

Atlanta (10-6) scored on the inside and outside, with an efficient attack that helped the Hawks overcome another big night from red-hot Boston guard Avery Bradley. Bradley scored 25 points to lead the Celtics, and he is averaging 22.4 points in his last five games. But he wasn't going to keep up with Atlanta, who shredded Boston's defense to shoot 56.3 percent from the floor at Philips Arena.

"This was an important game for us," Teague said. "It was a big-time game. We played well. We had to respond. When we went to Boston, they kicked our butt."

The Hawks took an 81-73 lead into the fourth quarter. Forward Mike Scott converted a three-point play off of nice pass from point guard Dennis Schroder to put the Hawks up 11 with nine minutes to play.

Guard Kyle Korver drained a couple 3-pointers in the fourth quarter as the Atlanta lead ballooned to 112-88 with three minutes left. Korver, forward Thabo Sefolosha and Scott each finished with 15 points.

"I know this, when your defense is a sieve, you're not a team," Boston coach Brad Stevens said, adding that if fines weren't involved, he would have left the bench and donned his casual post-game attire much earlier.

The Celtics (7-7) began the week with the NBA's top-ranked defense, but they didn't look like it early against the energetic Hawks, who pushed the pace from the opening tip. Atlanta scored a season-high 33 points in the first quarter and shot a sizzling 57.9 percent from the field in the first half. They led by as many as 13, but the Celtics made a move every time the Hawks tried to pull away, mainly thanks to Bradley.

Atlanta coach Mike Budenholzer said it was the best opening quarter of the season for the Hawks.

Bradley hit 8 of 12 shots in the first half, including three 3-pointers, to keep the Celtics somewhat close. Atlanta led 57-48 at halftime, behind 15 first-half points from Millsap.

After an 8-2 start, the Hawks had dropped four of five games and were looking for answers in the backcourt, where both Teague and key reserve guard Kent Bazemore had missed time with injuries. Guard Tim Hardaway Jr., an offseason acquisition, saw his first action of the regular season Tuesday. Hardaway finished with three points in 12 minutes.

"I think we competed for longer and better, and our focus and attention to detail was closer to where we needed to be," Budenholzer said. "We'll just continue to get more perfect, less mistakes."

Sefolosha filled the box score, adding seven rebounds, three assists, three steals and three blocks to his 15 points.

The Celtics, who, like the Hawks, have been up-and-down through the first month of the season, dropped their second straight game and third in their last four.

"I think we need to reconnect as a group," Stevens said. "I thought we did a lot of things on an island tonight. We've got to be a team. That's first and foremost."

Boston rookie guard R.J. Hunter, a local product who starred at Georgia State, scored 10 points. Point guard Isaiah Thomas added 15 points, and forward David Lee came off the bench for 10 points and six rebounds for the Celtics.

NOTES: Hawks coach Mike Budenholzer said he apologized to referee Ben Taylor for making contact with him while protesting a noncall Saturday in a loss to Cleveland. Budenholzer was fined $25,000, but not suspended by the NBA, a punishment that drew criticism from the referees' union. ... Boston guard Marcus Smart is sidelined for at least two weeks with a lower leg injury. Smart already missed three games earlier in the season with a sprained big toe. ... Only the Milwaukee Bucks had a worse rebounding differential than the Hawks (-5.7) entering Tuesday's games. ... The Celtics won the first of four meetings of the season with Atlanta, beating the Hawks 106-93 on Nov. 13. ... The Hawks retired the jersey of Hall of Fame center Dikembe Mutombo during a ceremony at halftime. NBA commissioner Adam Silver was among those in attendance to honor Mutombo.