Jimmy Butler led a fourth quarter comeback as the Philadelphia 76ers overpowered the Boston Celtics 118-115 in a stormy Eastern Conference duel on Thursday.

Butler scored 15 points in the final period as the Sixers overturned a nine-point deficit to seal their first win of the season against Boston while extending their winning streak to six games.

Butler, who was slow to settle in Philadelphia following his acrimonious move from the Minnesota Timberwolves in November, finished with 22 points including a decisive jump shot late in the fourth quarter.

Centre Joel Embiid also delivered a towering performance for the Sixers, finishing with 37 points, a career-high 22 rebounds and four assists.

Embiid was also at the center of the bruising encounter’s flashpoint in the third quarter which led to Celtics star Marcus Smart being ejected.

Replays appeared to show Embiid obstruct Smart with an elbow, prompting a furious reaction from the Celtics guard. Smart shoved Embiid forcefully to the floor after their collision, triggering a melee.

Embiid refused to react, and officials wasted no time in tossing Smart from the contest.

Boston meanwhile were left to reflect on a frustrating evening which saw them fail to capitalise on a big early lead of 60-46 in the second quarter.

Kyrie Irving led the scoring with 36 points for the Celtics, who fell to 43-28 with the loss. The 76ers improved to 46-25 to keep a firm grip on third place in the Eastern Conference table.

‘Unstoppable’ Embiid

Embiid meanwhile said he had been determined to produce a big performance after being riled by suggestions that the Celtics defense had his measure.

“I’ve been hearing that these guys can guard me better than anyone else, so I just had to come out and show that I’m the most unstoppable player in the league,” the 7ft tall Cameroonian said.

Celtics coach Brad Stevens took a dim view of Smart’s loss of control that saw him ejected.

“We needed him out there,” Stevens said. “We love all that Marcus is. And part of Marcus is his fire. A time or two a year, it gets the best of him.”

Embiid meanwhile had special praise for Butler’s decisive fourth quarter contribution.

“He’s a closer,” Embiid said. “My job is to get him in the forecourt and let him do his thing. The last few games he’s been fantastic.”

In other games on Thursday, James Harden exploded for 57 points but could not prevent the Houston Rockets stumbling to a shock 125-126 overtime defeat to the Memphis Grizzlies.

Harden’s half-century led the scoring but Memphis grabbed victory courtesy of 35 points from Mike Conley and 33 points from Jonas Valanciunas.

It was a similar story in Oklahoma City, where Russell Westbrook delivered a virtuoso display which ultimately proved to be in vain as the Thunder fell 123-114 in overtime to the Toronto Raptors.

Westbrook finished with 42 points, 11 rebounds and eight assists while Paul George had 19 points.

The Raptors however got over the line after an all-round offensive effort that saw all five starters make double figures.

Pascal Siakam led the scoring for Toronto with 33 points with support from Fred VanVleet (23) and Kawhi Leonard (22).

In Cleveland, Colin Sexton and the Cavaliers took full advantage of Giannis Antetokounmpo’s injury absence to score a 107-102 upset of the Eastern Conference leaders.

Cavs point guard Sexton led the scoring with 25 points while Jordan Clarkson had 23 off the bench to complete a remarkable reverse for the Bucks, who lead the standings with 53 wins and 19 defeats.

The Cavs meanwhile remain one place off the bottom of the East with the third worst record in the league, with 19 wins and 53 losses.

However a determined Cavaliers performance jolted the Bucks at the Quicken Loans Arena as the visitors struggled to adjust to the absence of Antetokounmpo, Malcolm Brogdon and Nikola Mirotic.

Khris Middleton led the scoring for the Bucks with 26 points and 12 rebounds while Eric Bledsoe added 24 with eight rebounds and eight assists.