Bam Adebayo delivered a 31-point masterpiece as the Miami Heat dug deep to defeat the Boston Celtics 109-103 on the road and take a crucial 2-1 lead in their Eastern Conference finals series on Saturday.

After an injury forced Miami talisman Jimmy Butler out of the game at half-time, Adebayo stepped up with a superb all-round display to hold off a ferocious Boston fightback at the Celtics' TD Garden. 

Adebayo, who had averaged just eight points a game in the first two fixtures of the best-of-seven series, finished with 10 rebounds, six assists and four steals in addition to his 31-point haul. 

"Those last couple of games, my team depended on me and I didn't show up," Adebayo said afterwards. "I took it upon myself to lock in and get the win."

"He did his version of what Jimmy does: 'do what's necessary for the game,'" Heat coach Erik Spoelstra said. "Tonight we needed the scoring and we needed that offensive punch early on."

Boston, who had routed the Heat to level the series in Miami on Thursday, were left counting the cost of 23 turnovers. 

The Celtics never led, but they cut a 62-37 deficit to one point, 93-92, with 2:40 to play on a 3-pointer from Jaylen Brown, who finished with 40 points. 

Max Strus answered with a 3 and then Adebayo bounced off defender Al Horford and made a basket at the shot clock buzzer to give Miami a six-point cushion.

Meanwhile, Miami's P.J. Tucker successfully bottled up Celtics star Jayson Tatum to deprive the home team of a crucial offensive weapon. 

Tatum finished with just 10 points from 3-of-14 shooting.

Game four of the series takes place in Boston on Monday.

(With input from agencies)