As the Celtics headed into a unique week that included a pair of two-game series, Joe Mazzulla wanted to treat the stretch with a playoff mindset.

On Tuesday night, they showed the killer instinct that has been a missing link that they’ve been missing over recent postseasons.

After a rare break that included three days off, the Celtics looked out of sorts in an ugly start. They trailed by as many as 15 in the first quarter as missed shots and turnovers piled up. But like they have more often than not this season, they responded. Shots finally started going down and with the game on the balance in a back-and-forth, playoff-like battle, they struck late as they pulled away for a 120-113 victory over the Cavaliers.

Jayson Tatum and Jaylen Brown each scored 25 points and Kristaps Porzingis added 17 – including 15 in the second half – as all five starters scored in double figures for the Celtics, who improved to 11-0 at home this season with the victory.

The game featured nine lead changes, the last of which came midway through the fourth quarter. In a back-and-forth game, the Celtics broke a 106-all tie with two free throws from Porzingis that sent them on a 9-0 run that gave them the separation they needed. Derrick White’s corner 3-pointer with 2:32 remaining put the Celtics up 10 and served as a dagger as the Celtics overcame their sloppiest start of the season. After missing their first nine shots from 3-point range, the Celtics made 18 of their next 35 from long range as they held off Donovan Mitchell and the Cavaliers.

Takeaways from the win:

– The Celtics’ starting five has been the best unit in the league by a wide margin to begin the season but they got off to an uncharacteristically poor start on Tuesday night. They looked out of sync on both ends of the court. Offensively, shots weren’t falling from anyone besides Jaylen Brown. While Brown started the game 3-for-3 from the field, all other Celtics started the game 0-for-14 shooting before Tatum’s layup with 2:23 remaining in the opening quarter. Kristaps Porzingis also made three bad passes that resulted in turnovers in the first four minutes. The C’s, who may have been rusty after six days off in the previous seven days, seemed disconnected defensively as they let the Cavs get some easy buckets. They trailed 18-4 at one point and by as many as 15 in the first quarter.

That’s why it seemed like a minor win for the C’s that they were down by 10 after one quarter.

– Despite a miserable start, the Celtics roared back in the second quarter thanks to stronger defense, hustle plays and finally, hitting some open shots. They forced three turnovers in the opening three minutes of the quarter as they went on a 10-3 run to force a Cleveland timeout.

Derrick White had another great stretch, hitting three consecutive 3-pointers midway through the second – all wide-open looks – in the span of 1:03. About a minute later, White made another impact play. After a Celtics missed shot, Jarrett Allen corralled the rebound but White snuck up behind him to steal the ball and then draw a foul, and he converted two free throws. The Celtics remarkably took a two-point lead with 1:39 remaining on a layup from Brown.

– With 1:17 remaining in the second, Brown landed awkwardly after missing a dunk and rolled his left ankle. Moments later, he left the game and headed straight to the locker room under his own power. But he recovered quickly and started the second half, when he scored the Celtics’ first five points.