Rookie Tyler Herro scored a career-high 37 points as the Miami Heat defeated the Boston Celtics 112-109 in game four of the Eastern Conference finals.
The Heat now lead the best-of-seven series 3-1 and can ensure their place in the NBA Finals with victory in game five on Friday.
Shooting guard Herro, 20, made 14 of 21 shots coming off the bench, while Jimmy Butler added 24 and Goran Dragic 22.
Jayson Tatum top-scored for the Celtics with 28 points, all in the second half.
On Herro, Heat coach Erik Spoelstra said: "He has a great competitive humility about him.
"He has a confidence. He has a fearlessness that is uncommon. But he's humble enough to work, to be coachable, to take the mentorship from the veteran players that we have on our team, and he just continues to gain more confidence as we go."
The Heat had held a 12-point advantage early in the third quarter before Tatum, who hadn't scored in the first half, came to life with 16 points in the period to narrow the gap to just a solitary point at the start of the fourth.
The Celtics surged ahead in the fourth quarter before a Bam Adebayo basket and five points from Herro, taking him to 30, restored the Heat's lead.
They led by nine points with 56.2 seconds left on the clock, but the Celtics could only reduce that to three by the time the buzzer sounded.
Game four of the Western Conference finals between the Los Angeles Lakers and the Denver Nuggets takes place on Thursday. The Lakers lead the series 2-1.