SAN ANTONIO -- Plenty is made about the offensive prowess of the Oklahoma City Thunder and their dual superstar scorers, Russell Westbrook and Kevin Durant.

Defense, though, especially in the final four minutes, was the key to Oklahoma City's 95-91 victory over the San Antonio Spurs on Tuesday that garnered the Thunder a 3-2 lead in the Western Conference semifinals.

Game 6 of the best-of-seven series is set for Thursday in Oklahoma City. A seventh game, if necessary, would be in San Antonio on Sunday.

Westbrook scored 35 points, including a crucial three-point play in the final seconds, and the Thunder outscored San Antonio 13-3 in the final 4:16.

San Antonio lost just once at home in the regular season but has been defeated twice at AT&T Center in the past eight days by Oklahoma City, which finds itself on the cusp of the Western Conference finals.

"We got stops and Russ was a maniac tonight," Durant said. "We didn't panic late in the game -- it was a good win for us. We did a good job of making them shoot mid-range shots and keeping them out of the paint. We just kept fighting."

San Antonio led 88-86 with 2:39 to play before Oklahoma City's Enes Kanter hit a layup, blocked a shot by the Spurs' Tim Duncan on the defensive end and ran the court to receive a pass from Westbrook for another layup that gave the Thunder a 90-88 lead.

San Antonio's Tony Parker hit a jumper to tie the game before the Thunder's Kevin Durant made two free throws to push Oklahoma City to a 92-90 advantage. Parker then went 1-for-2 from the line to bring the Spurs within 92-91, and, after a steal by Danny Green, badly missed a jumper with 11 seconds remaining.

Westbrook got loose on the ensuing inbounds play and headed to the basket as he was being fouled, converting the layup and a free throw with 6.3 seconds to play to ice the game.

Durant added 23 points for the Thunder, while Steven Adams had 12 points and 11 rebounds. Kanter pulled down 13 rebounds for Oklahoma City, and Westbrook contributed 11 rebounds and nine assists.

The Thunder outrebounded San Antonio 54-36, outshot the Spurs 43-6-39.8 percent and held the San Antonio bench scoreless in the second half.

"As the game wound down, we were able got to some loose balls and generate some extra possessions, and that's always critical," Thunder coach Billy Donovan said. "You are going to have nights that the ball doesn't go in, but the times we've locked up and played defense allow us to overcome that. We've given ourselves a chance the past few games because we've defended down the stretch. That's what we can control."

The Spurs were led by Kawhi Leonard's 26 points. LaMarcus Aldridge and Green had 20 points apiece.

San Antonio had won seven consecutive Game 5s, with its last Game 5 loss coming in 2012, to Oklahoma City.

"It's not like we got beat by 30 -- the game went down to the wire and both teams played really well," Spurs coach Gregg Popovich said. "You gotta make shots down the stretch, and sometimes things have to go your way. We lost a couple of boards there at the end, just like the last game."

San Antonio looked out of sync from the start of the game, falling into a 9-2 hole early in the first quarter. The Spurs fought back to take a 16-15 lead on a layup by Boris Diaw, but Oklahoma City scored the final seven points to reassume a 22-16 advantage after 12 minutes of play.

The Spurs ended the second period with a 12-4 run that was punctuated by a ringing 3-pointer by Green with seven seconds remaining, and the Spurs owned a 48-43 advantage at halftime. Leonard led all scorers with 17 first-half points, while Westbrook paced the Thunder with 14 points and Durant had 12 before the break.

Green's fifth 3-pointer of the game with 8:55 to play in the fourth quarter was countered on ensuing possessions by consecutive treys by Westbrook and Durant that tied the game at 78 and set the stage for the furious finish.

"We had a couple of plays (at the end of the game) when Oklahoma City did a great job defensively," Green said. "They took what we were looking for away -- they knew what plays were coming, you can hear them yelling from the bench and communicating."

The Spurs head to Oklahoma City with their season in the balance.

"I hope we respond by being a little angry and with a chip on our shoulder," Green said. "We have to go into their building and force another game back here. It's not over by any means. We have to stay positive and bring energy -- we've won there before, and we can do it again."

NOTES: Spurs C/F Tim Duncan, G Manu Ginobili and PG Tony Parker have 126 postseason wins together, the most by a trio in NBA postseason history. The trio has played in 195 playoff games. ... During Game 4 of the series on Sunday, Thunder F Kevin Durant equaled his postseason career high by scoring 41 points on 14-of-25 shooting from the field. In the fourth quarter alone, Durant outscored the Spurs (17-16) and made all six of his shots from the field. ... Durant's 29 second-half points in Game 4 represent the most in one half in a Thunder playoff game during the Oklahoma City era. ... Durant and PG Russell Westbrook have scored 25 or more points in the same postseason game 33 times, tied for the second most by a duo in NBA history behind the Lakers' Jerry West and Elgin Baylor (50).