OKLAHOMA CITY -- Late game execution has bedeviled Oklahoma City the entire season. It was the main reason they were a league leader in games lost after leading in the fourth quarter.

The problem reared its ugly head again in the final minutes of the Thunder's 100-96 loss to the San Antonio Spurs Friday at the Chesapeake Energy Arena. Turnovers, defensive lapses and poor offensive execution marked another ugly collapse.

Kawhi Leonard scored 31 points to lead the Spurs. He shot 9 of 17 from the field to go along with 11 rebounds and three assists. LaMarcus Aldridge added 24 points and eight rebounds. Tony Parker posted 19 points as the Spurs took a 2-1 lead in the Western Conference semifinal.

"It was great," Parker said. "I got a couple of more shots than usual. Just have to be aggressive. It's all about the team. Kawhi and LaMarcus, they were unbelievable. I just had to do my part."

Russell Westbrook paced the Thunder with 31 points on 10 of 31 shooting. He added nine rebounds and eight assists. Kevin Durant posted 26 points, five rebounds and three assists. Serge Ibaka scored 15 points on 5 of 6 shooting from the 3-point line.

Oklahoma City shot 41 percent from the field and only Durant and Westbrook took more than eight shots.

"That starts with me," Westbrook said. "Just too many shots. Got to get others guys involved."

The Thunder offense began to roll midway through the fourth quarter. Back to back 3-pointers from Ibaka and Westbrook and a baseline jumper from Durant gave them an 83-81 advantage.

After Aldridge scored, Durant hit another jumper and Oklahoma City led by two with 5:20 left in the game. But the Spurs quickly responded with free throws from Leonard and a Parker shot to retake the lead.

Aldridge and Leonard connected on four straight free throws that resulted from Thunder turnovers and bad offense. But Durant and Westbrook both scored to close the gap to 91-89.

Aldridge went to the line again, but only made 1 of 2 attempts. Yet another Thunder turnover led to a Leonard layup and a Spurs 94-89 lead. Another turnover by Oklahoma City gave David West a bucket. The Spurs went ahead by seven.

"Just a turnover," Westbrook said. "I can't turn the ball over, especially with the game on the line. Just have to do a better job, lock in. Take responsibility when the ball is in my hand s and make plays for my teammates. I didn't do that tonight."

Westbrook drained a pair of free throws before Durant stole the ball from Leonard. That led to another pair two free throws from Westbrook that cut the deficit to 96-94 with 46.7 seconds left.

The Thunder forced Aldridge into tough shot, which he missed. However. Leonard came up with the loose ball. Parker was fouled and he hit both free throw attempts to give the visiting team a four point advantage with 18 seconds left.

"It was a back breaker," Durant said. "We played good defense. We made them miss a shot. Then the ball kind of just fell in (Leonard's) hands. He was in great position to get the rebound. It sucks."

Oklahoma City used 14 seconds on the clock and came away with a Dion Waiters jumper. But Leonard put the game away with a pair of free throws.

"Just being strong mentally," Parker said of his team responding in the fourth quarter. "We know it's going to be a hard game, 48 minutes. Obviously it's a great building here, they great fans. It's very loud. We felt our execution got better and better. In the fourth quarter we got some stops. Offense was better than Game 2 in the fourth quarter."

Unlike the first two games of the series, both teams came out on the attack. This was especially true for Leonard who seemed to want to make amends for his for offensive performance in Game 2.

With Andre Roberson guarding him, Leonard looked for his shot early instead of waiting for it to come in the flow. He posted 11 first quarter points as the Spurs led 27-20.

San Antonio did a good job of neutralizing Westbrook. This force the ball out of his hands and made other players try and make plays. This led to a first half scoring drought of almost eight minutes that allowed the Spurs to take a 15 point lead.

With their offense not clicking, the Thunder turned to its defense to get them back into the game. They forced six first half turnovers and cut lead to 47-42 at halftime.

Oklahoma City was able to get back into the game despite Durant attempting only two free throws in the first half.

"I want to go back and look at the film," Thunder coach Billy Donovan said, "and see why Kevin's not getting to the line more than five times."

NOTES: Oklahoma City G Russell Westbrook is on pace to become just the third player in NBA postseason history to average at least 24 points, 10 assists and seven rebounds. The list includes Magic Johnson and Oscar Robertson. ... After scoring nine points in the first two games of the series, San Antonio G Tony Parker was asked if he needs to look for his shot more. "I don't really look for my shot," Parker said. "If it comes, and I can be aggressive, yeah. I think for us, my job as a point guard this year, it's been establishing LaMarcus (Aldridge) and Kawhi (Leonard). But I don't think that's my job anymore." ... Oklahoma City coach Billy Donovan said his team handled the three days between games well. "When you have three days, you try to utilize and maximize the best you can," Donovan said. "Find a balance between trying to stay sharp and trying to play a little bit. But also making sure guys are healthy."