Paul Pierce scored 21 points, moving nine behind Hall of Famer Larry Bird for second place on the club’s all-time list, and Ray Allen added 12. Rajon Rondo had 14 assists and reserve Chris Wilcox chipped in with 12 points.
Rudy Gay paced the Grizzlies with 21 points and seven rebounds, and O.J. Mayo scored 15 points for Memphis, which has lost six of eight.
Boston took charge with a 21-7 run early in the fourth quarter that turned a six-point lead to 90-70 on Garnett’s jumper.
Relying on a combination of reserves and two of their usual stars — Garnett and Pierce — the Celtics controlled the glass and outran the Grizzlies for transition baskets.
The Celtics led by six points at halftime and pushed it to double digits (53-43) on Pierce’s two free throws midway into the third. Boston relied on some hot long-range shooting in the third quarter, hitting 5 of its first 6 from behind the 3-point line to keep Memphis from coming back until Gay scored three consecutive baskets late in the period.
Allen hit three shots from beyond the arc and was fouled on one, hitting the free throw that made it 62-51. Pierce and Garnett also hit 3s, with Garnett’s just his third of the season on three chances, bringing a loud ovation from the crowd.
The Celtics held a 69-61 lead entering the final quarter.
Boston led 43-37 at halftime after the teams traded large second-quarter runs. The Grizzlies opened the period by scoring 16 of the first 19 points, taking a 32-27 lead on Dante Cunningham’s jumper.
After Celtics coach Doc Rivers called time out, his team responded with a 16-2 run — highlighted by a 7-0 spurt that was capped by a 3 by Allen from the left corner and Jermaine O’Neal coming down the lane for a dunk after a nice feed from Rondo, who had 10 assists in the opening half.
NOTES: Garnett also had 24 points in a New Year’s Day win over Washington. … O’Neal went to the locker room briefly late in the third quarter. … Memphis guard and former Celtic Tony Allen didn’t play because of a sore hip and knee, but he was in uniform on the bench. … Rivers said F Brandon Bass was out with “swelling of the knee.” Rivers didn’t make it sound like it was serious. “I think it’s an accumulation of a lot of games,” he said. … The game started just after noon. “I don’t like ’em,” Rivers said of the earlier start. “I like them on the road. I think it favors the road team. You get on the bus and get ready.” … Bird had 21,791 points. Hall of Famer John Havlicek tops the Celtics’ all-time scoring list with 26,395. … Rondo played his second straight game after missing eight with a sore right wrist. He wasn’t wearing a brace like he did in Friday’s win over New York. … Gay came down awkwardly after hitting a jumper and limped for a few seconds, but stayed in the game.