The undermanned Celtics blew an 11-point fourth-quarter lead on Sunday as the Cavs rallied late for a 115-111 victory at Rocket Mortgage Fieldhouse. Donovan Mitchell scored 20 of his 35 points in the final frame, including 11 straight in the game-winning drive, helping the Cavs snap a two-game losing streak and stay ahead of Boston in the Eastern Conference standings.

Boston trailed by as many as 11 points in the first half after a sluggish offensive start and without Derrick White (sore foot) and Jaylen Brown (illness). The visitors ended the game with an 18-6 run midway through the second quarter and pulled Boston within two points at halftime.

The Celtics appeared to take control of the game with a 35-21 lead in the third quarter thanks to some red-hot shooting from Jayson Tatum. Boston led by as many as 14 points in the second half and had a 12-point lead with eight minutes to play before the Cavs and Donovan Mitchell came into play. The All-Star guard scored 20 of his team-high 35 points in the fourth quarter and helped the hosts take the lead again with a 21:8 run in the final minute of the game. From there, the Cavs made enough free throws to hold off Boston, going 10 of 10 from the free throw line in the final minute.

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The defeat ended the Celtics’ seven-game winning streak, although Jayson Tatum scored a team-high 33 points. Payton Pritchard also scored 17 of his 24 points in the fourth quarter, but it wasn’t enough to stop the Cavs’ momentum.

Boston is now 1.5 games behind Cleveland for the No. 1 seed in the East. Here are four takeaways from the Celtics’ loss on Sunday night.

The Celtics’ offense fails early and late without top weapons: Without two of their top scorers in white and brown, Boston’s offense struggled to find a rhythm in the first half. The visitors shot just 36.7 percent from the field before halftime and just 29.6 percent from 3-point range, their second-worst shooting performance in a first half this year. With second chances difficult to come by against the Cavs’ big frontcourt and no one making much contact with players, Boston’s offense struggled to put together a good showing for the first time all season, scoring in the Midway through the season, just three points in a six-minute stretch in the second half. Joe Mazzulla noticed the difficulties early on and continued to use single big lineups as the game progressed to try to create more spacing for Boston’s offense. In crunch time, however, he managed to double-bigs again, which didn’t pay off against the Cavs’ 3-point shooting.

Drew Peterson gets a surprise chance: With Boston thin on the wings, Peterson got the nod early in the second quarter and matched his career high in minutes in the second quarter alone. He hit his first 3-point shot attempt of the night in transition and held his own defensively against the Cavs’ wings, leading to Mazzulla sticking with him as Boston rallied with an 18-6 run in the second frame. Peterson’s 6-foot-7 size also proved useful on the glass (four rebounds). It was far from a perfect performance (a few difficult defensive moments), but Peterson held his own in his first meaningful NBA minutes. The fact that he got this chance doesn’t exactly bode well for reserve wings like Baylor Scheierman, Jordan Walsh or Jaden Springer, but it’s obvious that Peterson is the far more trustworthy shooter and spacer in this group right now. Peterson finished the game with eight points and four rebounds in 26 minutes.

Jayson Tatum catches fire in the third quarter: The Celtics took control of the game in the third quarter and Tatum’s fingerprints were all over the performance. The All-Star scored 17 of Boston’s 35 points in the frame, including the first eight points of the period. He made 6 of 8 from the field and knocked down all three of his 3s in the quarter, while also leading the team in rebounds and assists in the frame. The Celtics have played their best basketball all year with Tatum on the court, and his contributions were highlighted even more Sunday night when Boston’s other top scorers were sidelined. With Boston needing an offensive spark, Tatum was able to deliver and almost did enough to secure Boston a win.

Late disappointment on the defensive becomes apparent: The Cavs extended their lead in the fourth quarter (43 points) with 10 free throws in the final minute. However, the Celtics’ inability to get stops in crucial period of time was alarming in this game. The Cavs relied on Jrue Holiday and Kristaps Porzingis at multiple points in the pick-and-roll and then scored easy baskets at the rim after some blistering shots from the perimeter. It’s not worth getting too worked up about Mazzulla considering the Celtics are more vulnerable in a potential playoff matchup against the Cavs.