Jayson Tatum and Marcus Smart scored 21 points apiece to lead the Celtics to a 116-106 victory over the Cavaliers in Cleveland.
Al Horford added 19 points and eight rebounds for Boston, which put a stop to a four-game skid.
The Celtics are a game-and-a-half behind the Pacers for the fourth seed in the East and home court in the first round.
Collin Sexton scored 24 points for Cleveland in the loss. Jordan Clarkson racked up 18 points off the bench for the Cavs, who lost their third straight.