Jimmy Butler scored 41 points as the Miami Heat produced a devastating comeback to defeat the Boston Celtics 118-107 in their opening Eastern Conference finals series clash on Tuesday.

Butler led a revitalized Miami second-half display as the Heat transformed an eight-point half-time deficit into a double-digit lead against a depleted Celtics side at Miami's FTX Arena.

Trailing 62-54 at the break, Miami outscored the Celtics 39-14 in the third quarter to set up a victory that gives the Eastern Conference top seeds a 1-0 lead in the best-of-seven series.

Butler received scoring support from Tyler Herro, with 18 points, and Gabe Vincent with 17 points.

But the win owed as much to Miami's renewed defensive effort in the second half, with the Heat shutting down Boston's Jayson Tatum and forcing a series of crucial turnovers and 11 blocks throughout the game.

"The guys were just really disappointed at half-time," Miami coach Erik Spoelstra said.

"I barely needed to say anything. Everyone was just really disappointed at our defensive focus and effort," added Spoelstra, praising the leadership of Butler during the third-quarter blitz.

"Jimmy just inspired everybody in that third quarter," Spoelstra said.

"Every time and pocket in the game when we needed control, or to get the right shot, or make the right decision, Jimmy had his fingerprints on it."

Butler said Miami had decided to go back to basics in the second half.

"Keep the game easy, simple, learn to capitalize off their mistakes," Butler said. "That's what changed in the second half. I didn't change anything. I continued to play basketball the right way. Shoot the ball when I'm open, hit the open guy."

- 'Lost composure' -
The Celtics shrugged off the injury absence of Marcus Smart and Al Horford (Covid-19 protocol) to look the sharper side in the first half, taking a 10-4 lead in the opening minutes.

Miami were initially unable to cope with the movement of Tatum, who bagged a career-high 21 points in the opening two quarters, shooting nine-of-14 from the field.

Boston led by as much as 13 at one stage in the second quarter before Miami trimmed the deficit to eight points at the interval.

Robert Williams, starting in place of Horford, also delivered a big first-half performance with 5-of-5 shooting for 12 points as well as two crucial blocks to deny Miami.

But it was a different story after the break as Miami out-hustled the Celtics defensively while raining down a deluge of buckets.

An incredible 22-2 run changed the complexion of the game and powered Miami into a 12-point lead at 76-64.

A nine-point Boston run cut the Miami lead to three points at 76-73, but the Heat rediscovered their scoring momentum and pulled away once more.

Two more Butler free throws made it 93-76 heading into the fourth quarter, and a 17-point lead became 20 soon afterwards.

Boston chipped away at the Miami lead to get within single digits, but Miami held on to claim the series opener.

Boston coach Ime Udoka could not hide his disappointment at the decisive third quarter that changed the game. The Celtics outscored Miami in every other quarter.

"We just lost our composure," Udoka said. "We won three quarters other than that one. We semi bounced back in the fourth and played well again and matched their physicality. But 39-14 is tough to overcome.

"We had one poor quarter that hurt us and it was strictly from a physicality standpoint. It wasn't anything different that they did.

"They just came out and imposed their will. Disappointing that we came out as flat as we did.

"They increased the physicality and it made that much of a difference."

Game two takes place in Miami on Thursday.