Finally, Russell Westbrook stepped to the line and hit a pair of foul shots with 13.4 seconds left to hold off the Celtics.
Westbrook scored 31 points, including six free throws in the fourth quarter for the Thunder's only points over a nine-minute span, and Oklahoma City held on to beat Boston 89-84 on Friday night.
"We're not used to finishing games without Kevin Durant," Oklahoma City forward Thabo Sefolosha said. "Russell had to do it. It showed a lot about our team. It definitely gives confidence to a lot of guys."
The Thunder led by 10 points late in the third quarter and had an 83-74 edge after Westbrook made a pair of free throws with 7:11 left in the game. But they didn't score again until he made another pair with 4:30 left, and the lead was down to one point when he went back to the line with 13.4 seconds left.
Westbrook went 11-for-13 from the line, but he missed all seven of his field goal attempts in the fourth quarter. The Thunder missed their last 13 shots from the field, going without a basket for the last 9:28 of the game.
"I knew going into the game that we would have to play just an ugly game," Thunder coach Scott Brooks said. "But our guys really battled and picked up the effort throughout the game and it was a good win for us. Having KD and Jeff out, it's not the easiest thing to do."
Oklahoma City was playing without two of its top three scorers: Durant, the NBA scoring leader who has a sore left ankle, and Green, who has a sprained left ankle.
"It's not painful to watch when we're winning," said Durant, who played in all 82 games last season and the first 11 this year. "Of course I want to be out there and play with my team. I've got to make sure I'm healthy first, though."
Kevin Garnett scored 16 points for the Celtics, but had a season-low two rebounds after getting bonked in the head in the first quarter. Rajon Rondo had 14 points and a season-low seven assists and finished the game on the bench with an unspecified leg injury. Glen "Big Baby" Davis went 2-for-10 from the field and missed four free throws in the fourth quarter.
The defending Eastern Conference champions had won three in a row and eight of nine.
"It's historical: The Garden, the Staples Center," Westbrook said. "It's buildings like that you kind of get ready to play for."
The Celtics have dodged two of the top young players in the league this week. On Wednesday, No. 1 overall draft choice John Wall sat out the Wizards' game in Boston with a sprained left foot; the Celtics won that one 114-83, their biggest margin of victory of the season.
But the Thunder managed to overcome Durant's absence.
"We didn't start the game with the right mindset," Celtics forward Paul Pierce said. "We knew what they were going through. We kind of eased into the game."
The Thunder took a 77-67 lead near the end of the third when Westbrook lost control of the ball and it rolled over to Royal Ivey, who put up a desperation 3-pointer as the shot clock expired and smiled as it banked off the glass and through the net. Delonte West scored to make it 77-69 heading into the fourth.
It was a nine-point game with 7:11 left before the Celtics cut it to 83-79 on five free throws. It was still a four-point game when Davis missed both free throws, then went back to the line and missed one of two. West made a pair of foul shots to make it a one-point game with 76 seconds left.
But Ray Allen missed a 3-pointer that would have given Boston its first lead of the half. After Westbrook's free throws, West missed a 3 that would have tied it.
Garnett played just three minutes in the first quarter but returned in the second with a big bump on the back of his head.
"I didn't know if I should play him even though he played OK," Rivers said. "Still don't know if I should have played him."
Rondo came up limping during a timeout with 6:19 left to play in the fourth; he stayed in the game for another possession, then came out for West.
"He wasn't running right and had to come out," Rivers said.
The Thunder used three different starting lineups all of last season. They've now used three in the first 12 games this season. ... Boston's Shaquille O'Neal had 10 of his 11 points in the first quarter. ... The Celtics had trailed only once before at halftime. ... New England Patriots receiver Wes Welker, an Oklahoma City native, was in the crowd wearing a Thunder cap. ... It was Durant's first game out since he sat out seven in a row in March 2009. ... The Celtics missed their last nine shots as the teams combined for just 27 points in the fourth quarter.
Scott Van Pelt explains why the Warriors potentially losing to the Thunder would be different from other teams that have had great success in the regular season only to fall short in the playoffs.
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