“It felt good,” Walker said. “We played hard. We had a slow start, but we stayed together. That was the best part about it.”
Indiana led by as many as 14 points in the first half, but never led in the final 24 minutes in losing for the third time in four games.
Domantas Sabonis had 24 points and nine assists to lead the Pacers. Justin Holiday added 19 points and five rebounds.
A 12-4 run by the Celtics, capped by a driving layup by Walker, gave Boston a 110-101 cushion in the fourth quarter.
Indiana pulled within 112-109 on a layup by Sabonis with 1:23 to play. A turnover by Jaylen Brown then gave the ball back to Indiana.
Holiday missed a 3-pointer from the corner and Theis hit one on the other end. But on Indiana’s next possession Sabonis got a friendly bounce off the top of the backboard on a deep 3 that trimmed Boston’s lead to 115-112.
The Celtics nearly got an 8-second violation, but Walker hustled the ball up the court and was fouled, and connected on his two ensuing free throws with 11.6 seconds remaining to help seal it.
One of the things Celtics coach Brad Stevens believes has hampered his team at times is doing too much ball watching when primary scorers Jayson Tatum, Brown and Walker have the ball in their hands.
There was a lot more movement from their teammates, who pressed the action in the half court, aggressively attacking the interior of Indiana’s defense.
“It’s good to get a win in a day that ends in ‘y’ right now,” Stevens said. “We played closer to what we want, but still lets back it up with a bunch of games in a row of playing that way.”
The Pacers started fast, scoring the game’s first 12 points, which included a pair of 3-pointers and a three-point play by Myles Turner. Indiana’s lead grew as high as 18-4, but Boston responded by closing the quarter on a 28-13 run to take a 32-31 lead.
“There’s a lot of plays in the first half we’d like to have back,” Pacers coach Nate Bjorkgren said.
Tatum and Brown combined to shoot just 2 for 8 from the field for seven points in the period.
Most of the heavy lifting for the Celtics’ comeback came from another source. Their bench stepped up, contributing 27 points in the first half to help Boston take a 61-60 lead into the break.
For the night Boston’s reserves held a 39-34 edge in bench scoring, led by Robert Williams and Jeff Teague, who had 14 points each.