Jayson Tatum felt he played terribly but was happy to help the Boston Celtics edge the Milwaukee Bucks in an NBA thriller on Wednesday.

Tatum hit a three-pointer with 1.5 seconds remaining as the Celtics beat the Bucks 122-121 in both teams' opening games of the season.

Bucks star Giannis Antetokounmpo missed the second of two free-throws with 0.4 seconds remaining.

Tatum, who finished with 30 points on 12-of-28 shooting, was pleased with the victory.

"Brad [Stevens, head coach] drew up a play for me to get the ball and make a play. I don't know what my field-goal percentage was, but I know I played terrible," he told ESPN after his heroics.

"It's a team game and everybody contributed. First one of the season so it felt good to get a win."

Jaylen Brown led the Celtics with 33 points, while Antetokounmpo finished with a game-high 35.

Tatum said having the chance to hit the game-winner was a position he wanted to be in.

"Ever since I was a kid I always wanted to be in that position. I can live with the result," he said.

"If I make the right play and if it's a shot for me and if it goes down or not, that's what I work so hard for. In that position you've got to try to make the right play, if it's making a play for a team-mate or taking that last shot, you just want to be in that moment.

"JB [Brown] played great tonight, [Jeff] Teague, Tristan [Thompson], this was a big team win."