Shorthanded Celtics can’t close out Cavs as win streak ends in Cleveland

Down two of their top three scorers, the Celtics were unable to reclaim first place in the Eastern Conference on Sunday, falling to the Cleveland Cavaliers 115-111.

Boston squandered a 12-point fourth-quarter lead while starters Jaylen Brown and Derrick White sat out due to illness and injury, respectively.

In Brown and White’s absence, Mazzulla trotted out a new-look lineup, with Sam Hauser drawing his first start of the season and Kristaps Porzingis and Al Horford starting together for the first time since April. In a surprise move, Mazzulla also added Drew Peterson to his rotation and gave the deep reserve major minutes, including in crunch time.

Hauser and Peterson both set season highs for minutes played, and backup guard Payton Pritchard played his most of any non-overtime game. Pritchard scored 24 points, Jayson Tatum finished with 33 and eight rebounds, and Porzingis had his most productive outing of the season (21 points on 7-of-17 shooting, eight rebounds, three steals).

But the Celtics couldn’t overcome Donovan Mitchell’s 35 points and Cleveland’s 17-for-36 effort from 3-point range. The Cavaliers matched Boston’s total of made threes on 13 fewer attempts.

The loss snapped an NBA-best seven-game win streak for Boston, which entered Sunday a half-game back of Cleveland for first in the East. The two matchups between the conference front-runners this season have been decided by a total of seven points.

The Celtics looked flat in the opening minutes, missing their first five shots as Cleveland opened an early 8-0 lead. Porzingis finally broke the ice with a 3-pointer, after which the Celtics found a more consistent rhythm.

Porzingis scored nine first-quarter points and was Boston’s most efficient offensive option in the early going. His rim protection also was helpful against a Cavs squad that racked up 60 points in the paint during the teams’ first meeting.

A three by Pritchard eight minutes in gave the Celtics their first lead of the evening. Cleveland led 28-24 after one quarter.

When the second quarter began, Mazzulla reached to the lowest rungs of his depth chart and inserted Peterson, a second-year wing out of USC who’s played most of his meaningful professional basketball in the G League.

One of Boston’s three two-way players, Peterson entered Sunday with just 30 career NBA minutes played, most of which came in blowouts. Yet Mazzulla kept the slender 25-year-old on the floor for nearly the entire second quarter, only removing him for the final 0.3 seconds. He was a plus-2 in the frame as Boston fell into, then erased a double-digit deficit.

With 6.1 seconds remaining in the second, Peterson drew a foul after a Tatum miss and made both of his free throws, sending the Celtics into halftime down 51-49. Peterson played another 13 minutes in the second half, finishing with eight points on 2-of-6 shooting (2-of-5 from three), four rebounds and one steal.

Boston dominated the third quarter, outscoring Cleveland 35-21. Tatum provided 17 of those points on perfect 6-for-6 shooting, and Hauser was a difference-maker at both ends with two made threes and two steals. Luke Kornet, a healthy DNP in Friday’s win over Chicago, denied three Cavaliers shots after checking in late in the quarter, including a flying dunk attempt by Donovan Mitchell.

The Celtics center celebrated that rejection with Dikembe Mutombo’s signature finger wag.

But just as they did in their visit to TD Garden last month, the Cavs rallied. Down 12 with eight minutes to play, they staged a 9-0 run, then pulled even at 101-101 with 1:37 remaining when Mitchell shook loose from Jrue Holiday’s perimeter defense and drained a three.

Tatum couldn’t convert contested layups on the Celtics’ next two possessions, and Cleveland got quick buckets from Mitchell and Evan Mobley to go up 105-101. Two Porzingis free throws made it a two-point game with 26.2 seconds remaining, and two more by Mitchell stretched the lead back to four.

Pritchard, who played the entire fourth quarter for the second straight game, scored eight points in the final 17.2 seconds, twice cutting Cleveland’s lead to one. But that was as close as Boston could get. Pritchard intentionally missed his final free throw and gathered his own rebound, but he illegally stepped into the lane before the ball hit the rim, resulting in a turnover.

Cleveland scored 43 points in the fourth quarter.

The loss kicked off the busiest week of the season for Boston — a five-games-in-seven-days sprint that includes two back-to-backs. The Celtics will host Miami on Monday, Detroit on Wednesday, Milwaukee on Friday and Memphis on Saturday.

Porzingis and Horford both typically do not play on consecutive nights, so Mazzulla might need to get creative with his lineups again when the Heat visit Causeway Street, especially if Brown and/or White remain unavailable.

White watched Sunday’s game from the Boston bench, wearing a David Pastrnak Bruins jersey and no visible boot or brace on his sprained right foot.