Kristaps Porzingis added 19 points as Boston won its ninth straight and closed out a 13-1 March.
Ja Morant scored 26 points, Santi Aldama 21 and Jaren Jackson Jr. added 20 points and 15 rebounds as the Grizzlies closed within seven points with three minutes left, but couldn't complete the comeback in losing for the sixth time in seven games.
The Celtics were without Jaylen Brown (right knee impingement) and Luke Kornet (ill).
The last two quarters were played with two officials after Matt Kallio did not return for the second half. The NBA said Kallio stayed in the locker room with an apparent injury.
Takeaways
Celtics: Boston is comfortably in second place in the East and the winning streak has solidified that position.
Grizzlies: Interim coach Tuomas Iisalo is looking for his first win after two games as Memphis (44-31) is getting dangerously close to the play-in game.
Key moment
With Memphis still within single digits, Boston opened the final frame shooting 4 of 6 from long distance and built its biggest lead midway through the fourth.
Key stat
Memphis was shooting 50% from 3-point distance midway through the second quarter when it built an 11-point lead. But the Grizzlies missed their last six 3-pointers in the half.
Up next
Boston hosts Miami on Wednesday. Memphis hosts Golden State on Tuesday.
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AP NBA: https://apnews.com/hub/nba
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