Los Angeles, United States — The Boston Celtics crashed to their first loss of the season in a stormy 120-102 road defeat to the Chicago Bulls on Monday that saw head coach Joe Mazzulla and star power forward Grant Williams ejected.

After opening their campaign with three straight wins, the Celtics looked poised to deliver another statement victory as they sprinted into a 19-point lead midway through the first quarter at Chicago's United Center.

But Chicago regrouped swiftly and stifled the Celtics' offensive game to come roaring back in the second quarter, outscoring the visitors 35-15 to open up a 65-54 lead at half-time.

The Bulls added another 35 points in the third quarter to romp into a 21-point lead heading into the fourth.

By that stage Celtics interim head coach Mazzulla had already been tossed from the game, ordered back to the locker room after backing star Jayson Tatum's questioning of a refereeing decision.

A grim night for Boston got worse early in the fourth quarter when Williams was also tossed for bumping into referee Cheryl Flores as he got to his feet.

Williams remonstrated furiously before storming off down the tunnel to jeers from the Chicago crowd.

DeMar DeRozan led the scoring for Chicago with 25 points while Ayo Dosunmu added 22 points.

Zach LaVine (19 points), Nikola Vucevic (18) and Derrick Jones Jr. (10) also made double figures for the Bulls.

Tatum (26 points) and Jaylen Brown (21) led Boston's scorers.

Mazzulla blamed his ejection on a loss of composure.

"It's unfortunate," he told reporters. "We have to be composed in all situations.

"Regardless of what happens, we have to be better, more composed, and it starts with me."

Mazzulla was also dismayed by the defensive shortcomings that allowed Chicago to come back after the Celtics' fast start.

"I think we just let go of the rope defensively," Mazzulla said.

"When you get off to a great start like that you have to continue to play, especially on the road."

In Memphis, Ja Morant and team-mate Desmond Bane scored 38 points each as the Grizzlies overpowered the Brooklyn Nets 134-124.

It was another barnstorming performance from Morant, who has averaged just over 34 points per game in four outings this season.

However, the 23-year-old star was forced to share top billing with team-mate Bane, whose 38-point haul included 8-of-10 from three-point range.

Brooklyn kept in touch with the Grizzlies throughout thanks to 37 points each from Kevin Durant and Kyrie Irving.

It marked the first time since 1983 that four players in one game have scored 35 points or more.

Irving described the third quarter which saw Memphis pile on an eye-watering 45 points as "horrendous."

"When you give up 39 points in the first quarter and 45 points in the third quarter — that's just not a trait of a great team on the defensive end," Irving said.

Irving reserved special praise for Grizzlies talisman Morant.

"He's an incredible student of the game and he takes his craft very seriously," Irving said.

"A trait of a great player is that they don't have fear — and Ja doesn't have any fear, night-in, night-out."

In Portland meanwhile, the Trail Blazers maintained their perfect start to the season with a 135-110 blowout over the Denver Nuggets.

Portland improved to 4-0 after restricting Nuggets star Nikola Jokic to just nine points.

Damian Lillard — who had scored 41 points in back-to-back games heading into Monday's fixture — led the scoring for the Blazers with 31 points.

Lillard was one of six Portland players in double figures, including Anfernee Simons with 29 points and Jerami Grant 21 points.

The Philadelphia 76ers finally got off the mark with their first win of the season in a 120-106 defeat of the Indiana Pacers.

James Harden led the Sixers' scorers with 29 points while Joel Embiid added 26, including a perfect 9-of-9 from the free-throw line.

In Miami, Fred VanVleet and Pascal Siakam combined for 47 points as the Toronto Raptors defeated the Heat 98-90 in a low-scoring game.

Toronto snatched victory after outscoring Miami 27-14 in a decisive fourth quarter that saw Nick Nurse's men rain down five three-pointers.