Paul Millsap insists he feels no extra pressure.

With the season-ending injury to Al Horford, the Hawks forward has delivered when the Hawks have needed him. They needed him in a big way Tuesday.

Millsap scored a season-high 34 points and had 15 rebounds for the Hawks in a 92-91 win over the Celtics at TD Garden. Millsap helped the Hawks overcome some dreadful early shooting and an 11-point fourth-quarter deficit. He scored eight points in the final-period rally.

“I don’t think about it,” Millsap said of taking over for Horford. “I just play basketball. For me, it’s just getting out there and doing what I’ve been doing.”

Millsap has averaged 28 points and 11.7 rebounds in three games without Horford.

The Hawks trailed by 18 points in the first half. They battled back and took the lead in the third quarter. The Celtics rallied again and went up by 11 points with 6:28 remaining.

Kyle Korver started the game-winning rally. After missing his first five 3-point attempts, he finally connected from 25 feet and was fouled by Gerald Wallace. After the free throw, an 11-point deficit was down to a manageable seven. It started the Hawks’ 19-8 run to end the game.

“I don’t know what to say about it,” Korver said. “I was glad one finally went in. I had the whole section over there reminding me that I hadn’t made a 3 all night. It was a great look. It was a decent look. I was shooting the ball flat all night. I tried to put it up a little bit higher, and I got the foul, too.”

The Celtics still had a chance. They took a 91-90 lead with 1:36 left when former Hawk Jordan Crawford scored at the shot-clock buzzer.

Jeff Teague made two free throws for the final margin. The Hawks had a chance to put the game away when they failed to convert a 3-on-1 break and couldn’t chase down several loose balls.

Crawford had a final chance, but couldn’t get a shot off with Shelvin Mack in his face.

“I knew with four seconds left, it was going to be hard for him to make a play with someone else,” Mack said. “I understood that he was going to try to take that shot. I did my best to contest it. With only four seconds it’s kind of hard to catch it and swing it without rushing it.”

The Hawks (18-14, 6-10 road) snapped a three-game losing streak to the Celtics and a four-game slide at the Garden. Teague added 16 points and Korver 14, including the 3-pointer that extended his NBA-record streak to 101 games.

The Celtics (13-18) lost their fourth in five games. Kelly Olynyk led the Celtics with 21 points, 10 in the fourth quarter.

The Hawks fell behind by 18 points in the first half. The Celtics used a 21-3 run between the first and second quarters to take the substantial lead.

The Hawks ended the second quarter on a 15-2 run, fueled in part by two 3-pointers from Cartier Martin, to close to within five points at intermission, 44-39.

Even with the run, the Hawks shot 21 percent (6-of-29) in the second quarter. The Hawks first-half point total matched their season low, done in two other games.

The Hawks scored the first six points of the third quarter, making the run 21-2, to take the lead 45-44 early in the period. It was the Hawks’ first lead since they led 12-10. They would have a 30-6 run for a six-point lead, 54-48, before the Celtics got back on track with nine consecutive points, two 3-pointers and a three-point play.

The Hawks are 2-1 in games without Horford and still trying to figure out life without the organization’s anchor.

“I think the next few games and the ones we just played without him are crucial,” Millsap said. “Really trying to figure out where we are going to go and how we are going to do it. We are figuring it out now. We are a scrappy team.”