OKLAHOMA CITY, Okla. — In a reunion with his former Boston teammates, Kendrick Perkins and the Oklahoma City Thunder got just the kind of victory he enjoys most.

Kevin Durant had 23 points and 11 rebounds, Russell Westbrook scored 15 points and Thunder beat the Celtics 91-79 on Sunday to stretch their winning streak to five games.

Boston was able to slow the Thunder from their best-in-the-NBA scoring pace of 107 points per game, but Oklahoma City's lowest output since Jan. 13 was still enough to come out ahead in this one.

"I told the guys coming into this game that it's going to be one of those low-scoring games, one of those nights that we have to grind out, so that's what we did," said Perkins, who won the 2008 NBA title with Boston. "Every night, we can't go out and expect to put up 100 points and the score to be 120-100. Some nights, it's going to be like this."

The Thunder limited Boston to 25 percent shooting in the second half after the Celtics shot 51 percent in the first. Boston dropped off to 33 percent in the third quarter and all the way down to 18 percent in the fourth, when the game got away.

"We were bad all game offensively," coach Doc Rivers said. "We were forcing things and offensively the ball stuck at times. Their length bothered us at times. Sometimes you want to win too bad, and that was us today."

Oklahoma City used an 11-2 run at the start of the fourth quarter to close it out. The Celtics had pulled within 68-65 after three quarters before going without a basket for the first five minutes of the fourth, and they never could recover.

Paul Pierce had 20 points to lead Boston, which had its own run of five straight wins broken. Kevin Garnett chipped in 10 points and 11 rebounds.

The Celtics finished at 38 percent shooting for the game with 19 turnovers, more than four above their average, while falling to 14-5 since All-Star Rajon Rondo's season-ending knee injury.

"We're showing that we can compete against pretty much anyone, but we have to bring our A-game most of the time, and that involves not turning the ball over and not fouling as much," said Pierce, who needs 10 points to pass Charles Barkley for 20th on the NBA's career scoring list.

It was the third-lowest scoring total of the season for Oklahoma City, which had 84 in its season-opening loss at San Antonio and 87 in a win at Portland in January. Boston even managed to outscore the youthful Thunder 11-8 on the fast break, but that slower pace still wasn't effective.

"This is what I like being a part of. All of that up and down fast pace, I kind of like the 'slow down, let's bump a little bit' type of game," Perkins said. "Either way, it's all good."

Jeff Green had a right-handed, reverse dunk as Boston closed the third quarter with six straight points and get within three. But the Thunder answered right back to start the fourth.

Backup point guard Reggie Jackson, who played at Boston College, got a running flip to go in and followed that with a double-clutch jumper from the right wing at the shot-clock buzzer.

When Jackson missed a more conventional shot, Nick Collison grabbed the offensive rebound and found a cutting Kevin Martin for a layup that turned into a three-point play and a 79-67 lead with 8:36 remaining.

"I was pretty upset with myself that it even came down to those type of shots, but I'll take them," Jackson said. "I guess I'll take them."

Martin added 12 points off the bench for Oklahoma City, which moved to 28-4 at home. The Thunder finish a run of four games in five days Monday night at San Antonio, with a chance to tie the Spurs — without All-Star point guard Tony Parker — for the best record in the Western Conference.

"It's important, no matter how guys try to look at it," Perkins said. "You always want home court as many playoff series as you can. We are going in there to try to get the win, and it's very important."

NOTES: Green got a round of applause when he checked in midway through the first quarter, playing in Oklahoma City for the first time since being traded in February 2011. A few moments later, Jason Terry — a member of Dallas' 2011 championship team that beat the Thunder in the West finals — was booed, and he put his palms up, acknowledging the fans' grudge. ... When 38-year-old Derek Fisher checked in for the first time, Celtics coach Doc Rivers greeted him this way: "No retired players." ... The Celtics signed D.J. White to a second 10-day contract. Fellow reserve Shavlik Randolph is nearing the end of his 10-day deal. "We've had so much change over the last three or four weeks with different guys, I just like the continuity now," Rivers said.