BOSTON -- Boston's early shooting troubles went away after halftime, while its defense and rebounding never faltered.
"We had to play really well to win, which was very concerning the way we were scoring in the first half," Boston coach Brad Stevens said. "But we played really well in every other area and then when we started scoring, it was good. It was a good game for us."
The Hawks played without coach Mike Budenholzer, who returned to Atlanta earlier Friday for a family emergency. Assistant Kenny Atkinson coached the team.
Atlanta trimmed Boston's 15-point lead to three late in the fourth quarter, but the Celtics shut out the Hawks the rest of the way.
"We stayed composed," Thomas said. "They made their run but we didn't panic. Young teams usually panic."
Boston did not panic, even after making only 17 of 50 shots in the first half. The Celtics shot 50 percent in the third quarter and held off the Hawks down the stretch. Boston finished with a 17-5 advantage on offensive rebounds and had only 10 turnovers to the Hawks' 17.
Paul Millsap led Atlanta with 14 points and eight rebounds, but scored only four in the final three quarters. Al Horford added 13 points, Kent Bazemore scored 12 and Kyle Korver finished with 11 points.
"We just didn't play very good. Sometimes that happens. I thought we made some mistakes that really hurt," Korver said. "I think that was the part that was most frustrating. We got ourselves back in position to win."
Kelly Olynyk led Boston's reserves with 15 points, including three 3-pointers.
After making just 17 of 50 shots in the first half, the Celtics went 14 for 28 in the third quarter. Boston forced Atlanta into eight turnovers in the period and capitalized on the Hawks' mistakes to pull ahead by 11 after a 45-all halftime tie.
Korver's 3-pointer with 5:21 left in the third put the Hawks up briefly at 60-59, then Boston started hitting from beyond the arc.
After putting up 50 attempts in the first half, the Celtics took 53 shots in the second. The volume helped Boston overcome the early troubles and the Celtics finished 42 for 103.
"We just had to go out and grind that one out," said Olynyk, who was 6 for 13. "If you're going to shoot 30 more shots than the other team, hopefully you're going to win."
Olynyk's math was slightly off -- Atlanta finished with 76 attempts.
BIG IN BOSTON
Atkinson said the Celtics were more physical through all four quarters and the Hawks struggled to match up inside. Millsap led Atlanta with eight rebounds and was one of five players with one offensive rebound.
"Sullinger is a big guy and Amir is a really good rebounder. Conversely, it's one of our weak points," Atkinson said.
Hawks: Budenholzer traveled with the team to Boston, then flew back to Atlanta on Friday. "Our thoughts are with him, obviously, and his family," Atkinson said. "We're all pretty close." The Hawks gave no additional details and asked fans and media to "respect the private nature of the situation." ... Dennis Schroder and Thabo Sefolosha scored 10 apiece for Atlanta. ... Jeff Teague, who came back in the second half after twisting his left ankle, finished with six points.
Celtics: G Avery Bradley sat out his second straight game with a bruised lower left leg. ... The Celtics called for a moment of silence before the national anthem in recognition of the dead and wounded during the attacks in Paris earlier Friday.
Hawks: Host Utah on Sunday.
Celtics: Visit Oklahoma City on Sunday night.