Jayson Tatum scored 33 points as the Boston Celtics ended the Cleveland Cavaliers' 15-game unbeaten start to the season with a hard-fought 120-117 victory in the NBA Cup on Tuesday.

The Celtics unleashed a barrage of 22 three-pointers to overwhelm Cleveland, who clawed their way back to within two points of the lead late in the game after trailing by 21 early in the second half.

Despite the Cleveland fightback reigning NBA champions Boston held their nerve and kept the scoreboard ticking over to close out a deserved win.

Tatum's 33 points included six three-pointers while the Boston star added 12 rebounds and seven assists in an all-round Celtics effort that saw six players finish in double figures.

Tatum said Boston's championship pedigree had helped the Celtics over the line as Cleveland threatened late in the game.

"We've played a lot of basketball, we've played in the biggest games," Tatum said.

"NBA is a bunch of talented teams -- guys are gonna make plays, they're gonna make shots.

"I say it all the time -- how you respond shows your growth and how special your team is."

Tatum admitted that ending Cleveland's unbeaten record, which has left them sitting on top of the Eastern Conference, had motivated the Celtics.

"They came in 15-0 feeling like they were the best team. We felt like we were the best team -- it's all competition. We were ready to play today," Tatum said.

Cavaliers coach Kenny Atkinson said his team had been caught off-guard by Boston's superior intensity.

"They had playoff force and physicality, we had regular-season force and physicality," Atkinson said. "That's why we were down by whatever we were down. Second half we turned it up, but it was kind of too late.

"We're just going to have to put it in the bank and make adjustments."

Tatum drained a superb three-pointer in the final seconds of the first half to give Boston a commanding 65-48 lead at the break.

The Celtics stretched into a 21-point lead early in the second half, but the Cavaliers clicked into gear and came roaring back to close the gap to two points at 88-86.

Tatum though had the last word, nailing an imperious three-pointer to give Boston a five-point lead heading into the final quarter.

A nip-and-tuck final period saw Cleveland repeatedly close to two points but Boston pulled clear in the final minutes to seal victory.

Donovan Mitchell led Cleveland's scoring with 35 points while Evan Mobley added 22 with 11 rebounds and six assists.

Westbrook bags 200th triple

In other games, Russell Westbrook became the first player in NBA history to amass 200 career triple-doubles, finishing with 12 points, 10 rebounds and 14 assists as a depleted Denver Nuggets overpowered the Memphis Grizzlies 122-110.

In Dallas, Luka Doncic finished with 26 points as the Mavericks crushed the New Orleans Pelicans 132-91.

The San Antonio Spurs shrugged off the absence of French star Victor Wembanyama to record an impressive 110-104 defeat of the Oklahoma City Thunder.

The Los Angeles Lakers extended their recent unbeaten streak to six games with a 124-118 win over the Utah Jazz.

Rookie Dalton Knecht was the star for the Lakers, scoring 37 points from 12-of-16 shooting while LeBron James and Anthony Davis each scored 26 points.

In New York, the Brooklyn Nets defeated the Charlotte Hornets 116-115 after a 34-point display from Cameron Johnson.

The NBA Cup was introduced last season as a way of providing a knockout competition in the early months of the league season.

All 30 league teams are drawn into six groups of five, with eight teams advancing to single-elimination knockout rounds.

The semi-finals and final take place in Las Vegas on December 14-17.

© Agence France-Presse