Game 5 is in New York on Tuesday night, when the Nets will try to advance to the Eastern Conference semifinals for the first time since 2014.
Jayson Tatum scored 40 points for the Celtics, following up his 50-point effort in a Game 3 victory.
Harden threw in 15 points with six assists in the quarter, and Irving scored 11 to help the Nets pull away, turning a 34-33 deficit at the start of the quarter into a 45-37 lead. They made it a 13-point game at the half.
Nets: Durant’s 17 points were the most in the first quarter for a Net since Kenyon Martin’s 17 in Game 4 of the 2002 NBA Finals against the Lakers. The Nets had 100 points through three quarters of a playoff game for just the second time in history.