Jayson Tatum spun in for a buzzer-beating layup to give the Boston Celtics a dramatic 115-114 victory over the Brooklyn Nets on Sunday in the first game of their NBA Eastern Conference playoff series.

Tatum scored 31 points to lead the Celtics, who thwarted a fourth-quarter comeback bid by the Nets to take a 1-0 lead in the best-of-seven series.

The reigning champion Milwaukee Bucks and Eastern Conference top seeds Miami also won their playoff openers.

The Bucks, led by NBA Most Valuable Player award contender Giannis Antetokounmpo, beat the Chicago Bulls 93-86, and the Heat dominated the Atlanta Hawks 115-91.

In Boston, Tatum added eight assists and two blocked shots, Jaylen Brown added 23 points, and Al Horford and Marcus Smart scored 20 apiece for the Celtics, who took a 96-85 lead into the fourth quarter but trailed 114-111 with less than a minute to play.

Former Celtic Kyrie Irving, booed throughout by Boston fans who still resent his departure for Brooklyn, led the Nets with 39 points. Kevin Durant was the only other Nets starter in double figures with 23.

Irving will no doubt hear from the NBA after a middle-finger salute to heckling fans in the third quarter, but he saved his best gesture for the fourth period, when he scored 18 points to key the Nets’ comeback bid.

Irving’s long three-pointer over Smart put Brooklyn up 114-111 with 1:04 to play.

But the Celtics clamped down defensively and pulled within one on Brown’s driving layup. After Durant missed a three-pointer, Tatum, fed by Smart from across the lane, willed his way through traffic for the game-winner.

“When he took that dribble, we just kind of made eye contact and he made a great pass and I just had to make a layup,” Tatum said of the final play.

A first half that featured 17 lead changes ended with the score knotted at 61-61, but the Celtics, who had been idle since their last regular-season game as the Nets battled through the play-in tournament, pulled away with a 39-24 third quarter.