James Harden had a new friend he called his good-luck charm in the arena, and the grit he needed to turn in a vintage effort — in the form of tying and winning shots —for the 76ers.

Looking down-and-out in the previous two games, Good Game James saved the 76ers in Game 4.

Harden hit the floater with 16 seconds left in regulation that tied the game, buried the go-ahead 3-pointer with 18 seconds remaining in overtime and scored 42 points to help the Sixers stave off a wild Boston Celtics comeback in a 116-115 victory on Sunday.

“I just want to win,” Harden said. “Today was do-or-die for us.”

The 76ers tied their playoff series at 2-2 with Game 5 set for Tuesday.

Harden won the game in front of John Hao, a paralyzed Michigan State shooting survivor who developed a long-distance friendship with the 10-time All-Star. Harden invited Hao to a game as soon as he was able to travel.

“He’s strong, he’s bouncing back, he’s recovering very well,” Harden said. “I feel like it’s my job to give him that light, that smile that he deserves. Hopefully today was one of those days where he can smile.”

Harden waved over Hao and signed his game-worn sneakers moments after Marcus Smart’s potential winner was a tick too late. The 76ers are now guaranteed to return home for Game 6 on Thursday.

Jaylen Brown said his poor defensive read when he ditched Harden to try and double Joel Embiid was a pivotal moment.

“It’s a gamble at the wrong time and a big shot by James Harden,” he said. “That’s my fault. I take full accountability.”

The Celtics did almost all they could to snuff out that chance. Smart and Jayson Tatum keyed a Celtics rally from 15 points down with 2 minutes left in the third quarter.

suns 129, nuggets 124 >> Devin Booker had 36 points and 12 assists and Kevin Durant also scored 36 points and Phoenix beat Denver to even their Western Conference semifinal playoff series at two games apiece.

Backup guard Landry Shamet made four crucial 3-pointers in the fourth quarter to keep the Suns ahead. Denver lost despite a huge game from MVP runner-up Nikola Jokic, who poured in 53 points on 20-of-30 shooting.

Jokic used his physical play to knock down several big buckets, even ripping the ball away from Suns owner Mat Ishbia at one point after the ball went out of bounds, which earned the Nuggets All-Star a technical foul.

The series returns to Denver for Game 5 on Tuesday.

The Suns took a 98-92 lead into the fourth quarter after a scoring flurry from Booker, who had 17 points in the third. Phoenix wouldn’t trail in the fourth, though Denver didn’t go quietly.

The Nuggets trailed 116-106 with 4:55 remaining but never panicked, slowly cutting into the lead. They pulled within 123-120 with 22.4 seconds left but TJ Warren made two free throws to push the margin back to five.

Booker — averaging 36 points on 60% shooting in these playoffs — was hot once again, shooting 14 of 18 from the field, including 3 of 4 on 3-pointers. Shamet finished with 19 points.