Dallas, Texas - Poised for an NBA coronation in Dallas, the Boston Celtics instead suffered the most lopsided Finals loss in franchise history, but with a 3-1 series lead, Jaylen Brown says there's no need to panic.

"These are the moments that can make you or break you," Brown said after the Mavericks demolished the Celtics 122-84 in game four of the best-of-seven championship series.

"We have to reassemble," Brown said. "We have to look at it and learn from it, and then we've got to embrace it and attack it.

"It's going to be hard to do what we're trying to do. We didn't expect anything to be easy, but it's no reason to lose our head."

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Boston forward Jayson Tatum said the key to moving past the big defeat was "not to harp on it too much."

"We're not making any excuses," Tatum said. "We need to be better, and we will."

Certainly, the Celtics still have the upper hand heading into game five on Monday, where they'll try to clinch a record-setting 18th NBA crown.

After all, no team has come back from 0-3 down to win an NBA playoff series.

But a Celtics squad schooled by coach Joe Mazzulla on the hunting tactics of killer whales looked more like the hapless seal pups on the beach as Luka Doncic, Kyrie Irving and the rest of the Mavs roared to a 38-point game-four win.

It was the third-largest margin of victory in Finals history and the worst pounding the 17-time champion Celtics had ever taken in the title series – surpassing their 137-104 loss to the Lakers in game three in 1984.

The Celtics won that series in seven games, and they still have three chances to close out the Mavs.

But from talk of a sweep, the question now is, could they become the first team to blow a 3-0 series lead?

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Dallas, meanwhile, knows the magnitude of the task they face.

"History is going to be made either way," said Mavericks guard Kyrie Irving, who won a title alongside LeBron James in Cleveland in 2016. "We'd like to be on the right side of it.

"We waited until game four to ultimately play our best game," Irving added. "Took long enough for all of us to get the party together and to play for each other the way we did [Friday]. But it's definitely a possibility that we can replicate it."

Irving will have to perform better than he did in games one and two in Boston, where Celtics fans still bitter over his 2019 exit after a two-year tenure with the team, hounded him relentlessly.