BOSTON — Isaiah Thomas scored 28 points, including a corner 3-pointer with 30 seconds left in overtime that clinched the victory as the Boston Celtics beat the Atlanta Hawks 104-95 on Sunday night to send their first-round playoff series back to Atlanta tied two games apiece.

Paul Millsap scored 45 points for the Hawks – a career playoff high and one off his all-time best – and added 13 rebounds.

Marcus Smart scored 20 points – including 11 straight for Boston in the fourth quarter – and Jonas Jerebko had 16 points and 10 rebounds.

Game 5 is Tuesday night in Atlanta.

The Celtics led by four with under a minute to play in regulation before Jeff Teague hit back-to-back 3-pointers to give Atlanta the lead. But Thomas drove for a layup to tie it 92-all with 15 seconds left.

The Hawks had a chance to win in regulation, but Teague lost control of the ball as he was going up for a shot in the final seconds.

Boston’s Amir Johnson scored the first five points of overtime. Teague kept Atlanta in it with a fourth-chance 3-pointer with 3:44 left, but the Hawks did not score again.

It was 97-95 with 1:34 left when Evan Turner, who finished with 17 points, made a jumper. Thomas got open in the right corner and made a 3-pointer to give Boston a seven-point lead.

Teague, who started the game 1 for 10 from the floor, had only 13 points but made a 3 with 50 seconds remaining in regulation to cut Atlanta’s deficit to one point, then and another with 21 seconds to play to give the Hawks the lead.

Thomas scored a career-high 42 points in Game 3 when the series came to Boston and the Celtics avoided a 3-0 deficit. But he spent a night worrying whether he would be suspended for taking a swing at Atlanta’s Dennis Schroder in the first quarter; he got the word Saturday afternoon that he would be able to play.

Schroder was booed when he entered the game. He was given a technical foul with 0.6 seconds left in the first half when he shoved Jae Crowder.

Thomas missed the foul shot, keeping Atlanta’s lead at 48-46 going to halftime.

The Hawks scored 13 of the last 18 points in the first half and then the first 14 in the second, turning a six-point deficit into a 16-point lead.

Jerebko had a pair of 3-pointers in the last 90 seconds of the third quarter and the first two baskets of the fourth to help Boston turn an 11-point deficit into a 74-73 lead.

NOTES: Millsap had 26 points in the first half and surpassed his previous playoff high of 29 before the first timeout in the third quarter. … Some of the biggest cheers were for the Patriots sitting courtside: Owner Bob Kraft, Coach Bill Belichick, tight end Rob Gronkowski and running back LeGarrette Blount. … Kelly Olynyk returned to action for the Celtics after missing the previous two games because of a shoulder injury. He played four minutes and had zero points and two rebounds.