PHILADELPHIA — Save this performance for the highlight reel: Clutch shots. A raucous home crowd. The type of comeback that embodies a team’s toughness.

Yes, it was a victory in a festive atmosphere worthy of a playoff bound team, though it was the so-so 76ers – not first-place Boston – that made a dogged push for a go-wild win.

Robert Covington made the go-ahead 3-pointer late in the fourth quarter to lead the Philadelphia 76ers to a 105-99 win over the Boston Celtics on Sunday.

Dario Saric scored key baskets to extend the lead and bolster his bid for NBA Rookie of the Year. Saric scored 23 points and helped rally the Sixers from a 13-point hole in the third.

“I think the toughness and determination that they repetitively show isn’t a fluke, it’s who they are,” Coach Brett Brown said.

Covington buried a 3 with 3:37 left that put the Sixers up 94-91 and Nik Stauskas hit his own with 38 seconds left for a 103-97 lead that sent fans inside a packed Wells Fargo Center into a frenzy.

The Sixers thumped Dallas 116-74 on Friday night and improved to 17-19 at home. The Sixers won 10 games total last season.

The Celtics, still with a nice lead in the Atlantic Division, won the first three games of the season against the Sixers.

“Finally, we beat them,” Saric said.

Al Horford led the Celtics with a season-high 27 points in a game Boston could not afford to waste.

Boston guard Isaiah Thomas sat out a second straight game with a bone bruise on his right knee and was questionable for Monday’s game at Washington. The Celtics could surely use their leading scorer (29.2 points) against the Wizards. Boston and Washington are jostling for a top three seed headed into the Eastern Conference playoffs.

Horford came up empty in the clutch with a scoreless fourth quarter.

“Guys are really looking for me. I’m just trying to make plays,” he said.

Just not enough of them.

Saric waved his arms told the crowd of 19,446 and urged them to get louder down the stretch of Philadelphia’s fantastic comeback. Jahlil Okafor, the No. 3 overall pick in the 2015 draft, sat out the second half for the Sixers because of right knee soreness.

The Sixers were just fine without him.

Jae Crowder, who scored 15 points, kept Boston in the game with a couple of late clutch 3s that never should have been necessary.