The Cleveland Cavaliers’ historic 15-game unbeaten start to the season ended with a narrow 120-117 loss to the defending NBA champions, the Boston Celtics, at TD Garden on Monday.

The Cavaliers had made NBA history earlier in the week, becoming just the fourth franchise to go 15-0 to begin a campaign, following their win over the Charlotte Hornets.

However, the Celtics, led by Jayson Tatum’s dominant performance of 33 points, 12 rebounds, and seven assists, ended the Cavs’ remarkable streak.

Boston had built a commanding 17-point lead by halftime, but the Cavaliers mounted a spirited comeback in the second half.

Cleveland’s Evan Mobley played a key role in the fightback, contributing 22 points, 11 rebounds, and six assists. The Cavaliers came within two points midway through the final quarter, but the Celtics managed to hold on for the win.

“Everybody knew that they were undefeated and coming to our building,” said Celtics guard Derrick White.

“And it’s an NBA Cup game, and we already lost one. So, it was a really big game in that aspect. We were all aware.”

The win for the Celtics was important in the NBA Cup, as they had already suffered a loss in the tournament earlier this season.

Elsewhere in the NBA, the Los Angeles Lakers extended their winning streak to six games with a 124-118 victory over the Utah Jazz.

Rookie Dalton Knecht, the 17th pick in the 2024 draft, had a career-high 37 points and tied a rookie record by hitting nine three-pointers in the victory.

The Denver Nuggets defeated the Memphis Grizzlies 122-110, while the Dallas Mavericks cruised to a dominant 132-91 victory over the New Orleans Pelicans.

The NBA Cup, introduced in 2023 and won by the Lakers last season, counts towards the regular-season standings but does not impact the NBA Championship race.