The Celtics will face the winner of the Western Conference Finals, where the Dallas Mavericks hold a 3-0 lead over the Minnesota Timberwolves ahead of Tuesday's game four.

The Celtics win in Indianapolis was their seventh straight in the post-season but they left it late against a Pacers team again without injured star guard Tyrese Haliburton.

Jaylen Brown once again proved decisive.

He hit a step-through to level at 102-102 with 2:40 left in the fourth, then superbly rose to block Andrew Nembhard at the rim.

With 45 seconds remaining Brown found Derrick White in the corner who sank the three-point jumper that ultimately clinched the game -- and the series.

Nembhard, who had 24 points, 10 assists and six rebounds for the Pacers, missed a three-pointer with 33 seconds left which would have tied the game.

Brown led Boston's scoring with 29 points and Jayson Tatum had 26 points, 13 rebounds and eight assists.

The Celtics return to the finals two years after losing to the Golden State Warriors as they search for their first NBA title since 2008.

"It's been nothing but a grind, we haven't skipped no steps all season," said Brown, named the Eastern Conference Finals MVP after averaging almost 30 points through the series.

"We've got a bunch of great guys in this locker room, tough guys. Our coaching staff has been great, front office great and now we want to take the next step," he added.

Boston have gone 12-2 throughout the post-season as they beat the Miami Heat, Cleveland Cavaliers and the Pacers to reach their 23rd NBA Finals in franchise history.

Celtics head coach Joe Mazzulla paid tribute to his team.

"Look at all the talent, look at the players that we have. It's really all about them, they let us coach them. They allow us to push them, they listen to us and they set the temperature of the organization every single day," he said.

"As a coach, the greatest gift you can have is a group of guys that trust you and that allow you to coach them," he added.

- Pacers upbeat in defeat -

It was the third time in the four series games that Indiana had lost after holding leads or being tied in the final minute of a game.

The Pacers had led by nine with 8:28 left in the fourth but without the influential Haliburton they were unable to see the game out.

"An amazing season, a magical season. The level of fight was just tremendous all the way through this," said Pacers head coach Rick Carlisle.

"Circumstance never fazed them one way or the other.

"They were in this to win every possession that they could and in any game that they could, and so a lot of respect to our players and just how they conducted themselves in this series," he said.

"There are a lot of things accomplished this year. Expectations will be raised for next year, which is good," added Carlisle.