LOS ANGELES (AFP) — The Boston Celtics crashed to their first loss of the season in a stormy 102-120 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 halftime.

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 fired 19 points, Nikola Vucevic had 18 and Derrick Jones Jr. chipped in 10 for the Bulls.

Tatum and Jaylen Brown led Boston's scorers with 26 and 21 points, respectively.

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.