BOSTON -- Evan Turner called Boston Celtics teammate Marcus Smart the best player on the court Sunday night at TD Garden.

He probably was right -- and this was in a game that saw Atlanta Hawks forward Paul Millsap go off for 45 points.

Smart scored 20 points, grabbed eight rebounds, handed out five assists and played great defense on Millsap, as the Celtics, down by 16 in the third quarter, evened the best-of-seven, Eastern Conference first-round playoff series at two games apiece with a 104-95 overtime win.

Millsap scored only two points over the final 5:33 of regulation and the entire overtime.

Smart, only the second player since 1992 to register at least 28/8/5 off the bench in an NBA playoff game, scored 11 consecutive points for the Celtics in the fourth quarter. He then opened the overtime with a pair of assists to Amir Johnson. Boston never trailed in the OT, during which Atlanta hit just one of its 11 shots.

Smart, fined $5,000 for flopping in Game 3, admitted he was a little surprised when coach Brad Stevens told him to try to stop Millsap, who totaled just 26 points in the first three games of the series before erupting.

Stevens said, "Obviously, you're throwing darts a little bit with a guy that's rolling like that."

Said Smart, who is 4 inches shorter and 40 pounds lighter than Millsap: "Just (tried) to really stop and make it hard for him, pressure him and really contest every shot that he took."

Stevens added, "When you've scored 45 through three quarters, you probably are a little winded."

Millsap said, "I blame myself for not being aggressive down the stretch and not putting the ball in the hole."

Johnson scored Boston's first five points of overtime, and Isaiah Thomas (team-high 28 points) nailed a 3-pointer from the right corner to ice the game with 30 seconds left.

With both teams holding serve on their home floors, Game 5 is in Atlanta on Tuesday night.

"It's our turn to respond," Hawks coach Mike Budenholzer said. "That's how the playoffs are, they are hard, and it's never easy in the playoffs. So now we go home, and that's a big challenge for us."

With New England Patriots owner Robert Kraft, coach Bill Belichick, tight end Rob Gronkowski and running back LeGarrette Blount cheering on the Celtics from courtside, Boston rallied after a hot second-half start by Atlanta.

"They're fighters. They never give up," Stevens said of his players.

When the game ended, Thomas took his shirt off and gave it to Blount.

Atlanta thought it took a one-point lead on a Kent Bazemore 3-pointer with 1:52 left in the OT, but a review correctly overturned the basket on a 24-second violation.

Thomas, who sank two free throws with 20.3 seconds left, added six assists and four rebounds. He paced Boston with 42 in the Game 3 win. Turner delivered 17 points, seven rebounds and six assists, and Jonas Jerebko had 16 points and 10 boards in his second consecutive double-double as a starter.

Jae Crowder had 12 points, and Johnson finished with nine points and nine rebounds for Boston.

Jeff Teague had 13 points and five assists for the Hawks. He was 1-for-10 from the floor before he calmly drained two 3-pointers in the final minute of regulation to give his team a 92-90 lead.

Thomas then tied the game with a drive with 15 seconds left. Teague was isolated with the ball before he lost control as time ran out in regulation.

"Jeff had the opportunity to take a guy (Thomas), he had a good look, but the ball slipped out of his hand," Millsap said.

Hawks center Al Horford, playing despite a groin injury, grabbed nine rebounds but scored just five points in the loss.

Atlanta guard Dennis Schroder, booed loudly by the Boston crowd whenever he entered the game or touched the ball because of his battles with Thomas in Game 3, was 3-for-13 from the floor and scored just seven points off the bench. He also picked up another technical foul.

Teague finished 4-for-18.

Millsap was 10-for-32 from the floor and 2-for-9 from 3-point range in the first three games -- including 4-for-21 and 1-for-7, respectively, in Game 2 and Game 3. However, he went 11-for-16 in the first half and finished 19-for-31 Sunday.

"It doesn't matter if you don't win," he said of the 45 points, just one off his career high.

In the end, the Hawks fell to 0-6 on the season in overtime games; they haven't won one since March 2014. They also lost each of their past five playoff OT games.

NOTES: San Antonio's Manu Ginobili is the only other reserve besides Boston G Marcus Smart to post at least 20 points, eight rebounds and five assists in a playoff game since 1992. Ginobili has done it twice. ... Celtics F Kelly Olynyk, who missed the previous two games due to a shoulder injury, entered the game with a minute left in the opening quarter. He logged just 3:35 and finished with no points and two rebounds. ... Hawks coach Mike Budenholzer on Boston PG Isaiah Thomas getting no punishment for whacking Atlanta PG Dennis Schroder in the head in the first quarter of Game 3: "The NBA always does a thorough job. Their job is not easy, and they cannot make everybody happy."