Trailing by 17 in the second quarter and down 60-47 at halftime, Miami thrashed the Celtics 37-17 in the third quarter and held on for the victory.

Bam Adebayo scored 15 of his 21 points in the Heat's blistering third quarter.

The Celtics, who let a big lead slip in a 117-114 game one overtime defeat on Tuesday, regained the lead in the fourth quarter and were up 94-89 with 4:25 left to play.

But the Heat chipped away with a  hook shot from Adebayo and a steal and dunk by Jimmy Butler.

Goran Dragic followed up two free throws with a three-pointer over Boston big man Daniel Theis that put the Heat ahead 100-95 with 1:42 remaining and Miami powered to the finish line.

Dragic finished with 25 points, and Duncan Robinson added 18, all on three-pointers.

Adebayo added 10 rebounds and four assists, Jimmy Butler had 14 points, four rebounds, three assists and four steals.

"We like to make it hard for ourselves," Butler said of the Miami "comeback kids."

In fact, the Heat got off to a brisk start making five of their first six three-point attempts.

After a close first quarter the Celtics surged ahead in the second period, only for the Heat to make the needed adjustments at halftime.

"You get to the conference finals, it's not all about you," Heat coach Erik Spoelstra said. "Boston had a lot to say about how that first half was going. That was them putting us on our heels."

Kemba Walker broke out of his scoring slump with 23 points for the Celtics. Jaylen Brown and Jayson Tatum scored 21 apiece.

But Brown missed a three-pointer that would have tied it with 15.1 seconds to play and 20 Celtics turnovers led to 26 Miami points.

The Heat will try to take a stranglehold on the best-of-seven series in game three on Saturday in the NBA's quarantine bubble in Orlando.

The Celtics will go into that one knowing that no NBA team has rallied from an 0-3 deficit to win a series.