PHILADELPHIA (AP) — Boston had an NBA opening week it would love to do over: Gordon Hayward, its prized free-agent signing, was lost to a gruesome injury, and the Celtics lost their first two games.

But when the Celtics were on the ropes against a 76ers team looking to prove "The Process" is more than a catchphrase, Kyrie Irving gave a glimpse why he may be the man in Boston that he so longed to be in Cleveland.

Irving scored 21 points and Al Horford had 17 as the Celtics won for the first time since losing Hayward, 102-92 over Philadelphia on Friday night.

The Celtics lost to Cleveland in their opener when Hayward went down with a mangled ankle that may cost him the season, and then lost to Milwaukee. Horford and Irving took over down the stretch to quiet a raucous 76ers' crowd in the home opener.

Irving made the shots he needed to make in the fourth.

Jayson Tatum scored 15 points and had Terry Rozier III had 14 to keep the Celtics afloat with a makeshift lineup. Boston snapped a tie game with an 11-4 run late in the fourth that steadied a franchise still reeling from Hayward's injury.

Joel Embiid knows the feeling of missing an entire season. The Sixers center missed his first two NBA seasons with foot injuries and was limited to 31 games last year. Healthy and ready to play, Embiid had one of his worst offensive games as a pro, with 11 points on 4-for-11 shooting. He strayed from the low post and missed all six 3s in 28 minutes.

"They didn't do anything. I was open," Embiid said. "All the 3s I took, I was wide open."

Moments after he checked in late in the third, Embiid drove past Horford for his first basket of the game and a 65-56 lead. Embiid missed his first eight shots — he spent more time exhorting the fans to chant "Trust the Process," — before he gave the fans a real reason to cheer. He did grab 14 rebounds.

Already playing short-handed, the Celtics wasted points with a 15-of-25 effort from the line through the third quarter. Aron Baynes slipped in for a tip-in at the horn when Embiid failed to box out that cut Philly's lead to 72-69.

"We're figuring out a lot of newness," Irving said. "It's not always going to be perfect."

J.J. Redick led the Sixers with 19 points.

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