"He's had a tough week," Celtics coach Brad Stevens said. "We took him out of the starting lineup. Tonight, we put him back in and he responded. He anchored our defense, especially in the fourth quarter."
The Celtics, who had lost six straight, entered the fourth quarter trailing 74-64.
But a strong defensive effort resulted in a stretch of 11 straight scoreless possessions for the Hawks at one point and just 13 points for Atlanta in the final quarter.
"We have to be great defensively for us to have any success," Bass said. "We do not have All-Stars at the offensive end where we don't need to play defense. Everybody has to be on point on both sides of the ball for us to get wins."
Al Horford led the Hawks with 18 points and seven rebounds, and Jeff Teague had 13 points and 10 assists. Atlanta had won four of five games before losing for just the second time this season at home.
Trailing 85-84 with 3:17 to play, the Celtics scored seven straight to take a 91-85 lead with 46 seconds left. Jordan Crawford scored five points during the run,
"When we were down, I was kind of the reason," said Crawford, who scored 10 of his 12 points in the fourth quarter.
"I was the only one kind of struggling on offense, trying to find my shot. So I just wanted to make the effort to try to get to the hole, try to make a couple plays."
The Hawks broke open a tight game by closing out the third quarter with a 17-5 run that gave them a 74-64 lead.
Included in that run was a flagrant foul on Jared Sullinger that resulted in a three-point trip for the Hawks.
Teague had six points and an assist to spark the Hawks, while the Celtics floundered on offense, missing six of their final seven field goal attempts in the quarter.
It appeared as if a grueling stretch for the Celtics was catching up to them, as they were playing their fourth game in five nights in four different cities.
Early in the fourth, however, the Celtics put together a 10-0 run to make it a one-point game with 5:28 to play.
"It has really been quite a stretch (schedule-wise)," Stevens said. "(The Hawks) missed a few shots they normally make, and we played really well in the fourth quarter. If we don't have all hands on deck, it's not pretty. We had all hands on deck tonight."
The Celtics outrebounded the Hawks 47-38 and held the Hawks to 38.7 percent shooting.
"We showed great resolve," Bass said. "When things got tough, we stuck together. The losing streak was wearing on us. It was a great time to get a win."
"We need to get to the free throw line," said Hawks coach Mike Budenholzer, whose team was outshot 31-12 at the line.
"It's a tough lesson to learn. It's a tough way to learn it. For three quarters, we were efficient and we were good. But we weren't able to bring it home in the fourth quarter."
Hawks guard Kyle Korver hit a three-pointer in the first quarter, giving him 87 straight games with a three. He is two games shy of Dana Barros' NBA record of 89 straight. . Celtics rookie center Kelly Olynyk, who has started six games and is averaging 7.5 points, did not make the trip to Atlanta due to a sprained ankle. He will miss at least two weeks. ... This was Boston's second win over a team with a winning record. The Celtics beat the Heat earlier this season, also on the road.
Copyright by STATS LLC and The Associated Press
ATLANTA, GA - NOVEMBER 23: Shelvin Mack #8 of the Atlanta Hawks shoots the ball against the Boston Celtics on...