Boston Celtics' Kyrie Irving (11) reacts in front of Philadelphia 76ers' Jimmy Butler after making a 3-pointer in overtime during an NBA basketball game in Boston, Tuesday, Dec. 25, 2018. Boston won 121-114. (AP Photo/Michael Dwyer)
Boston Celtics' Kyrie Irving (11) reacts in front of Philadelphia 76ers' Jimmy Butler after making a 3-pointer in overtime during an NBA basketball game in Boston, Tuesday, Dec. 25, 2018. Boston won 121-114. (AP Photo/Michael Dwyer) Credit: ap photographs — Michael Dwyer

Boston — 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.

Joel Embiid led Philadelphia with 34 points, making 12 of 12 free throws, and pulled down 16 rebounds. Jimmy Butler scored 24, JJ Redick had 17 points and

Ben Simmons added 11 points, 14 rebounds and eight assists for the Sixers.

Simmons’ two free throws with 2:15 left to put the Sixers up 114-112, but Philadelphia didn’t score again.

“These are the type of games that challenge you mentally, and we made sure that we stayed with it and finished it,” said Al Horford, who scored just four points but pulled down nine rebounds and helped mitigate the Sixers’ size advantage inside.

The Celtics led 57-51 at halftime, but Philadelphia used a 15-2 run in the third while shooting 60 percent in the period and led 89-86 entering the fourth.

Philadelphia shot 60 percent in the third quarter, hitting five 3-pointers, and led 89-86 entering the final quarter.

It stayed tight through the end of the fourth. Chandler got open for a 3-pointer with 37 seconds left and the Sixers led 108-106, then Irving pulled up for a 13-foot jumper to tie it at 108 with 20 seconds left.

Redick missed a jumper just before the buzzer, and the game went into OT.

Rockets 113, Thunder 109

Houston — James Harden scored 41 points and Houston beat Oklahoma City for its seventh win in the last eight games.

Harden has scored 30 points or more in a career-high seven games in a row, marking the first time a player has done that since Russell Westbrook had eight consecutive 30-point games in November 2016.

A 3-pointer by Paul George with less than two minutes left got Oklahoma City within 4 before Harden missed a 3. Westbrook missed a shot for the Thunder, but George stole the ball from Harden and was fouled by him.

George made both free throws to get the Thunder within 2 with 43.6 seconds left. Harden then drove past George and into the lane for a layup to make it 112-108 with 20.4 seconds left.

Bucks 109, Knicks 95

New York — Giannis Antetokounmpo had 30 points and 14 rebounds in his Christmas debut, and Milwaukee celebrated its return to the holiday schedule by beating New York.

Brook Lopez scored 20 points for the Bucks, who played on Christmas for the first time since 1977.

They were selected for the showcase slate of games largely because of Antetokounmpo but the timing also was perfect to show an emerging team, which improved the NBA’s second-best record to 23-10.

Malcolm Brogdon finished with 17 points for the Bucks, who bounced back from a loss to Miami on Saturday to win for the fifth time in six games.

Rookie Kevin Knox scored 21 points for the Knicks, who have lost six straight Christmas Day games and fell to 22-31 in their NBA-record 53 appearances on the holiday.

New York has lost five in a row and 10 of 11 since rallying to stun the Bucks 136-134 in overtime on Dec. 1 at Madison Square Garden.

Lakers 127, Warriors 101

Oakland, Calif. — Los Angeles lost LeBron James in the third quarter to a strained left groin, then went out and beat the two-time defending champions without him, getting King James’ 17 points, 13 rebounds and five assists before the injury in a surprising rout of Golden State.

James grabbed at his left groin area with 7:51 left in the third after slipping under the Warriors’ basket while trying for a loose ball. He tried to stretch it out, awkwardly walked toward the Lakers bench trying to loosen up before leaving on his own though gingerly out the tunnel for the locker room.

Stephen Curry made consecutive 3s shortly after James exited, and the Warriors got within 78-76 at the 2:48 mark of the third — but Kyle Kuzma and the persistent Lakers stayed at it every possession.

Curry wound up with 15 points but the home fans had seen enough well before the final buzzer and headed out for the rest of Christmas.

Kuzma contributed 19 points with a pretty baseline 3 late, Ivica Zubac had 18 points and 11 rebounds and Rajon Rondo 15 points and 10 assists off the bench as the Lakers snapped an 11-game losing streak on the Warriors’ home floor since a 118-115 overtime win Dec. 22, 2012. Los Angeles also ended a seven-game skid overall in the rivalry with its first win in the series since March 6, 2016.

CELTICS 121, 76ERS 114, OT

BOSTON (AP) — Kyrie Irving hit back-to-back 3-pointers in overtime for six of his 40 points and the Celtics rallied to a win over the 76ers.

Irving, who forced the OT on a jump shot with 20 seconds left in the fourth, also pulled down 10 rebounds for the Celtics, who trailed 113-108 with 3:33 left in the extra period before rallying behind Irving down the stretch.

Ben Simmons’ two free throws with 2:15 left to put the Sixers up 114-112, but Philadelphia didn’t score again.

Irving’s 3-pointer with 3:01 left gave Boston its first lead of overtime at 115-114, then after a miss by Philadelphia, Irving hit another 3-pointer with 1:28 left and Boston fans leaped to their feet and cheered louder than they had all night.

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

ROCKETS 113, THUNDER 109

HOUSTON (AP) — James Harden scored 41 points and the Rockets beat the Thunder for their seventh win in the last eight games.

Harden has scored 30 points or more in a career-high seven games in a row, marking the first time a player has done that since Russell Westbrook had eight consecutive 30-point games in November 2016.

A 3-pointer by Paul George with less than two minutes left got Oklahoma City within 4 before Harden missed a 3. Westbrook missed a shot for the Thunder, but George stole the ball from Harden and was fouled by him.

George made both free throws to get the Thunder within 2 with 43.6 seconds left. Harden then drove past George and into the lane for a layup to make it 112-108 with 20.4 seconds left.

Westbrook made 1 of 2 free throws to cut it to 3 with 15 seconds left, and Austin Rivers made a free throw with 7.4 seconds left to secure the win.

George had 28 points and 14 rebounds for the Thunder, and Westbrook added 21 points with nine rebounds and nine assists.

BUCKS 109, KNICKS 95

NEW YORK (AP) — Giannis Antetokounmpo had 30 points and 14 rebounds in his Christmas debut, and the Bucks celebrated their return to the holiday schedule by beating the Knicks.

Brook Lopez scored 20 points for the Bucks, who played on Christmas for the first time since 1977. They were selected for the showcase slate of games largely because of Antetokounmpo but the timing also was perfect to show an emerging team, which improved the NBA’s second-best record to 23-10.

Malcolm Brogdon finished with 17 points for the Bucks, who bounced back from a loss to Miami on Saturday to win for the fifth time in six games.

Rookie Kevin Knox scored 21 points for the Knicks, who have lost six straight Christmas Day games and fell to 22-31 in their NBA-record 53 appearances on the holiday.

New York has lost five in a row and 10 of 11 since rallying to stun the Bucks 136-134 in overtime on Dec. 1 at Madison Square Garden.