"We missed Al's inside presence late in the game," Celtics center Kendrick Perkins said. "It's tough right now ... We are struggling and have to deal with it."
Atlanta opened the fourth quarter with a 10-0 run and took a 66-62 lead on a Johnson fadeaway jumper with 7:13 remaining in the game. Rajon Rondo sank two free throws 23 seconds later and ended a Celtics drought of 8:20 without a point.
"It feels good," Hawks swingman Josh Childress said. "This has happened to us so many times that it's nice when we do it to somebody else."
Johnson scored six straight points to cap the Hawks' 18-4 run that cut the Celtics' lead to 57-53 with four minutes remaining in the third quarter. Smith had 13 points in the period.
"When we were down 18, I thought we had dug ourselves a hole too deep," Smith said. "We at least wanted to get it down to six after three."
Perkins had a season-high 15 points and 12 rebounds for Boston, whose losing streak is its longest in seven years.
Atlanta missed its first eight shots and started the game 1-for-17 from the floor as they trailed 28-10 at the end of the first.
Perkins scored 11 points and grabbed 10 rebounds in the first half as the Celtics led 44-29 at the break. The 29 points tied a season low for the Hawks.
Jefferson finished with 11 points and 10 rebounds and has averaged 23 points and 15 rebounds over the last three games.
Brian Scalabrine returned to the Celtics' active roster after missing six games with a bruised knee. ... Smith was 0-for-6 in the first quarter. ... Atlanta has three road victories this season and has averaged 82 points over the last four games. ... Boston's franchise record for most consecutive losses is 13 in the 1996-97 season.