Boston didn't need overtime to beat Memphis for the second time in a week, although the Celtics may have felt like they went an extra round before finally putting away the Grizzlies.

Avery Bradley scored 23 points and Isaiah Thomas had 21 points and seven assists in the Celtics' 113-103 victory on Tuesday night. Boston led by just four points with 1:29 remaining, but clinched it with six straight free throws in the final minute.

"They made plays. We stood our ground and stuck out a win," said Thomas, who made all eight of his attempts from the foul line.

Boston made 19 of 21 free throws and outrebounded Memphis 47-37. The Celtics won for the sixth time in seven games and beat the Grizzlies for the second time in a week.

The Celtics needed overtime and a career-high 44 points from Thomas for a 112-109 win in Memphis on Dec. 20 and the rematch was almost as close.

Marc Gasol had 26 points and nine assists for Memphis. Zach Randolph scored 10 of his 16 points in the fourth quarter to help keep the Grizzlies close and pulled down 10 rebounds. Tony Allen had 17 points and eight rebounds for Memphis, which was coming off a 112-102 loss in Orlando the night before but hung with Boston until the final minute.

"They still scored way too many points to my liking, but I liked the fact that we came back and competed," Memphis coach David Fizdale said. "We didn't get the stops necessary like we usually do. But we gave ourselves a chance to win on the road and that's all you can ask for."

The Grizzlies have lost five of seven.

Gerald Green added a season-high 19 points for Boston, including nine in the fourth quarter.

"He just brought more intensity," said Marcus Smart, who scored 13 for Boston. "You could definitely tell that the intensity changed when he stepped on the floor."

After falling behind by 13 in the second quarter, Memphis pulled within 56-48 at halftime and cut the margin to 69-67 on Allen's layup with 5:16 left in the third.

Boston led 84-77 after three, but Randolph scored Memphis' first six points of the fourth and Gasol pounded the Celtics inside and out, converting a three-point play early and adding a 3-pointer with 5 minutes remaining to cut Boston's lead to 100-97.

The Celtics didn't falter, getting a pair of free throws from Green and a three-point play by Thomas to make it 105-97 with 3:06 left. They put away Memphis down the stretch after the Grizzlies pulled within 105-101 on a 3-pointer by James Ennis III.

TIP-INS

Grizzlies: Fell to 9-5 in December, remaining tied for the franchise record for most wins in the month. ... Mike Conley (left big toe), Chandler Parsons (rest) and Brandan Wright (left foot) did not dress. ... The Grizzlies, ranked second in the NBA in points allowed (97.7 per game), have given up more than 100 points in three straight and four of five.

Celtics: Kelly Olynyk picked up his fourth foul with 5:15 left in the second quarter. ... Green's previous high for the season was nine points. He scored 10 in the second quarter alone Tuesday and Amir Johnson, the only Boston starter not to score in double figures, pulled down 10 rebounds to go with his four points.

TOUGH D

Boston won despite committing 18 turnovers, including seven in the fourth quarter.

"We need to be stronger with the ball, including myself," Thomas said. "They're one of the top defensive teams in the NBA."

BACK-TO-BACK

The Grizzlies fell to 8-1 in the second of back-to-back games this season, although fatigue did not appear to be a factor. The Grizzlies answered each time the Celtics started pulling away right up until the final minute.

UP NEXT

Grizzlies: Host Oklahoma City on Thursday, then open a four-game California road trip at Sacramento on New Year's Eve.

Celtics: Visit the defending NBA champion Cleveland Cavaliers on Thursday night.