Kevin Durant beat the Dallas Mavericks again.

After burying a long three-pointer at the buzzer in the fourth game of the season against Dallas, Durant's go-ahead jumper with 1.5 seconds remaining lifted the Oklahoma City Thunder past the defending NBA-champion Mavericks, 99-98, in Game 1 of this Western Conference quarterfinal.

After reigning NBA Finals MVP Dirk Nowitzki gave Dallas the lead with a pair of free throws with nine seconds remaining in the contest, Durant heaved a high-arcing, off-balance floater from the foul line over the outstretched arms of two Dallas defenders.

The ball bounced high off the front of the rim, tantalizing the Oklahoma City faithful before hitting off the backboard and through the net, sending the jubilant home crowd into complete euphoria.

"They switched back (Shawn) Marion on me and he's such a real good defender. And I just didn't want to settle for a three so I just tried to take it closer and shoot a shot. I got enough arc on it and it was able to fall in," Durant said of his game-winning shot.

Dallas, which was out of timeouts, could not get a shot off before the final buzzer.

Durant finished the game with 25 points on 10-of-27 shooting to go with six rebounds and four blocks for the Thunder, who fell to the Mavericks in five games in last year's Western Conference Finals.

Russell Westbrook led all scorers with 28 points, while Serge Ibaka added 22 points and five blocks. James Harden made his first appearance since being elbowed by the Lakers' Metta World Peace last Sunday and scored 19 points off the bench.

Nowitzki netted 11 of his 25 points in the final five minutes to pace Dallas. Jason Terry buried four three-pointers en route to 20 points and Shawn Marion tallied 17.

Game 2 of this best-of-seven series is on Monday in Oklahoma City.

Nowitzki, the seven-foot German who closed out games by averaging 11.8 points in the fourth quarter during last year's series against the Thunder, nailed just his second field goal of the half -- a fadeaway from the left elbow -- for an 87-84 Dallas advantage with 4:22 left.

It was the start of a personal 9-3 spurt, and his pull-up jumper with 2:31 remaining gave Dallas a 94-87 lead.

But the Thunder netted the next seven. Durant started it with a pair of free throws, Ibaka finished a three-point play underneath and Harden's steal of Nowitzki led to a Durant dunk in transition, knotting the game at 94-94 with 1:27 to go.

Following a mad scramble for a loose ball on Dallas' next trip down the floor, Vince Carter fired from the right baseline with the shot clock running down. Ian Mahinmi snatched the offensive rebound, was fouled, and nailed two free throws, giving Dallas a 96-94 edge.

The pendulum then swung back in the Thunders' favor as Ibaka threw one down along the left baseline for another three-point play, making it 97-96 in favor of Oklahoma City with 53.9 to play.

After Nowitzki turned the ball over, Durant missed a floater from the baseline and Dallas called a timeout with 24 ticks remaining.

Nowitzki got the ball on the left elbow, maneuvered left before stepping through a double team and drawing a foul. He made both free throws for a 98-97 Dallas margin with nine seconds left.

But Durant, the seventh player in NBA history to win three consecutive NBA scoring titles, had the answer.

"We were right there," Nowitzki said. "We made some mistakes, (we) turned the ball over twice in the last three minutes when we were up seven."

Earlier, Terry poured in 10 first-quarter points off the bench as Dallas led, 26-22, after a quarter of play.

The Mavericks took a 51-48 advantage into the locker room and Marion tallied 10 points in the third as Dallas headed into the final frame with a 73-69 advantage.

Game Notes

Nowitzki averaged 32.2 points against Oklahoma City in last year's playoffs...The Thunder won three of the four meetings this season...Oklahoma City, which was on top of the Western Conference standings for most of the season, stumbled to a 7-7 finish. They lost the top seed in the West to San Antonio in the process...Dallas went 22-22 over its last 44 games.