OKLAHOMA CITY • Standing alone, 26 feet from the basket, Kevin Durant flicked his wrist and held his hand aloft as the ball curved from his fingertips and splashed through the net.

An ear-splitting, celebratory roar swelled up from the stands at Chesapeake Energy Arena.

This was an unexpected scene. It was only the second quarter in Game 6 of the National Basketball Association's (NBA) Western Conference semi-final match-up on Thursday between the Oklahoma City Thunder and the San Antonio Spurs.

The Thunder had built a 3-2 lead through the first five contests. The Spurs, facing elimination, had vowed to come out angry. They promised more energy, better execution.

That explained the feeling of delight and delirium in the crowd after Durant's basket, which came with two seconds left in the first half and capped a stunning 45-15 run. It gave Oklahoma City a 24-point half-time lead.

The Spurs, despite a frantic effort in the fourth quarter, never recovered, and lost 99-113.

It was odd to see and almost hard to believe: The team with the second-most wins in the league this season failing to escape the second round of the NBA play-offs.

The Spurs won 67 games during the regular season, second only to the Golden State Warriors' 73. They had the league's best defence, as well as a crisp and multi-pronged offence.

So the Thunder, the winners of 55 games and the No. 3 seed in the conference, were seen as the underdogs. They seemed talented but flawed - exciting, but ultimately inferior to the classy Spurs.

"Game 1 they just outplayed," Durant said of the Spurs, who won the series opener by 32 points. "Game 3, I think we gave the game away, and we didn't want to do that again.

"We were huge on the road, though. Russell (Westbrook) was huge last game. I think that propelled us into having a good game tonight.

"We're not done yet. We have to keep improving and get ready for the next series."

The Thunder will now meet the Warriors in Game 1 of the Western Conference finals on Monday in Oakland, California.

"Golden State's a great team," Thunder coach Billy Donovan said. "It will be a great challenge. We've got a little bit of time to get prepared before we play."

On Thursday, Durant was spectacular, scoring 37 points. Russell Westbrook added 28 points and 12 assists.

For the Spurs, the defeat may mark the end of an era. Never before had Tim Duncan, Tony Parker and Manu Ginobili - the core of four NBA championship teams - looked so collectively ineffectual.

"Everybody's disappointed - the only team that's not disappointed is the last team standing," Spurs coach Gregg Popovich said when asked about the season coming to an end. "Everybody loses but one."

For all the talk about the Spurs' versatility, their offence on Thursday was stuck on two options: midrange jumpers and isolated post-ups for LaMarcus Aldridge.

Kawhi Leonard scored a team-high 22 points. Duncan, in what could be his last game, scored 19 points and grabbed five rebounds. Aldridge had 18 points and 14 rebounds.

Popovich, meanwhile, flailed in hope of finding something, anything, to invigorate his group.

He played Kevin Martin, who had appeared for a combined 44sec in the previous four games, in the first quarter.

In the second, he put in the 2.13m-tall rookie centre Boban Marjonovic, who had played 44 seconds in the last three games. He used the 40-year-old point guard Andre Miller, who had not played since Game 1, extensively in the second half.

Nothing worked. The Thunder were too forceful, too dynamic.

NEW YORK TIMES, REUTERS