Jayson Tatum rediscovered his scoring touch with 31 points as the Boston Celtics thrashed the Miami Heat 102-82 to level their NBA Eastern Conference finals series on Monday.

Two days after dropping their opening home game of the best-of-seven finals, Boston came roaring back at the TD Garden with a one-sided game four blowout that squares the series at 2-2.

Tatum also finished with eight rebounds and five assists, with support coming from Payton Pritchard (14 points) and Derrick White (13). Jaylen Brown and Robert Williams added 12 points apiece.

Al Horford led a hard-nosed Boston defensive effort with 13 rebounds and four blocks.

Victor Oladipo led the scoring for Miami with 23 points from the bench.

None of Miami's starting line-up made double figures, making a paltry 18 points in total.

"We just came and redeemed ourselves," Tatum said.

"We knew this was a game that we really needed, to protect home court. After the last game we were just ready to play, to get back out here and play better.

"It's been a back and forth series so far. It's best of three now, we'll just go away now for game five and get ready."

Miami coach Erik Spoelstra said his team had never been able to recover from a poor start.

"They came out and jumped on us," Spoelstra said. "I think more than anything our offense hurt us at the beginning. We just weren't purposeful.

"But we're not making any excuses. They outplayed us tonight for sure. We never could get any kind of a grip on the game."

- Highs and lows -
Spoelstra insisted that his team would mount a response in game five.

"This is part of the playoffs. There's a lot of extreme highs and extreme lows, and a lot of emotion," said Spoelstra. "You just have to stay the course and stay together.

"And it's a great series. You have to embrace that."

The game was effectively won in the first two quarters as Boston punished a strangely subdued start by Miami to race into a 29-11 lead in the first quarter.

Tatum, who had been restricted to just 10 points in Saturday's game three defeat, was back to his sharp-shooting best with 12 points in the first quarter alone.

With Miami's offense unable to penetrate a Boston defense bolstered by the return of Williams, the Celtics kept the pressure on in the second quarter, extending the lead to 27 points at one stage.

There was no better illustration of Miami's offensive impotence than the first-half points haul of their starting line-up.

With Jimmy Butler contributing just six points, the Heat's starters totalled 10 points in the first half, with only Oladipo's 18 points off the bench preventing a total humiliation.

Miami made just 11-of-40 attempts from the field in the first half, a shooting percentage of just 27.5 percent.

Any hopes Miami had of mounting a second-half fightback were quickly snuffed out in the third quarter.

Boston outscored the Heat 12-4 immediately after the interval to pull clear by a whopping 32 points with the lead at 69-37.

The departure of Williams with what appeared to be left knee soreness midway through the third quarter helped Miami reduce the deficit to 23 points at 73-50, but it was only a temporary reprieve.

Boston continued to score steadily at the start of the fourth quarter and  were sitting on a 31-point lead at 88-57 with just under nine minutes remaining before closing out a wire-to-wire win.

The series now swings back to Florida, with top seeds Miami hosting game five on Wednesday.