In their first NBA playoff game, the Boston Celtics defeated the Brooklyn Nets 115-114 at the buzzer.
Tatum’s 31 points helped the Eastern Conference second seeds hold off a fourth-quarter comeback by the Nets.
The Celtics are up 1-0 in the best-of-seven first-round series.
Kyrie Irving, who led the Nets with 39 points against his former team, raised his middle finger to the Boston crowd during the third quarter.
Since his controversial departure in 2019, Irving has had a poor relationship with Celtics fans, who booed him throughout the game.
The Milwaukee Bucks, Miami Heat, and Phoenix Suns all won their first games of the season.
Giannis Antetokounmpo, one of three contenders for the NBA Most Valuable Player award this season, led the Milwaukee Bucks to a 93-86 victory over the Chicago Bulls.
The Heat, the Eastern Conference’s top seed, defeated the Atlanta Hawks 115-91, while the Suns, the Western Conference’s top seed, defeated the New Orleans Pelicans 110-99.
The Celtics trailed the Nets 114-111 with 45.9 seconds left in Boston, thanks to a three-pointer by Irving.
Celtics fans booed Irving, who led the Nets with 39 points. After Kevin Durant missed a three-pointer, a Jaylen Brown layup cut the lead to one, and Tatum scored the game-winning basket on a Marcus Smart pass.
However, the seven-time NBA All-Star emphasised that the contest should not be judged just on his fan connection.
Despite foul trouble that put him on the bench for much of the fourth quarter, Antetokounmpo led the Bucks to victory in Milwaukee with 27 points and 16 rebounds.
Nikola Vucevic led the Bulls with 24 points and 17 rebounds.
Duncan Robinson, a Miami Heat reserve, achieved a career-high with 27 points in the playoffs, helping his team to a strong defensive performance.
While the Hawks and their star guard Trae Young struggled, Jimmy Butler scored 21 points and PJ Tucker added 16.