BOSTON (AP) — Kyrie Irving extended the game with a clutch shot, then ended it with two more in overtime.

Irving scored six of his 40 points in overtime, hitting back-to-back 3-pointers while leading Boston back from a five-point deficit as the Celtics beat the 76ers 121-114 on Tuesday night.

“Just competition at its highest. I love going against the best. It’s not too often you get to do that in the regular season, especially on a holiday like Christmas,” said Irving, who also pulled down 10 rebounds. “I got to open presents with my family this morning then come into work. It was great.”

It came very close to not being so great for Boston, which needed Irving’s fadeaway jumper from 13-feet out to tie it at 108 with 20 seconds left in the fourth quarter, forcing the OT.

The Sixers, much improved from the team that lost here 105-87 in the season-opener, scored the first five points of OT, but could not stop Irving when they needed to — again.

“There aren’t many in his weight class,” Philadelphia coach Brett Brown said. “Inevitably, you’ve got to stop him.”

Irving hit a 3-pointer with 2:01 left to put Boston up 115-114, then struck again from 30-feet with 1:29 remaining in the OT and the Celtics held on to improve to 2-0 against Philadelphia this season.

Jayson Tatum and Marcus Morris scored 23 apiece for Boston and Terry Rozier had 10 points.