Kevin Durant scored 27 points and the Oklahoma City Thunder are one win away from the NBA Finals, beating the San Antonio Spurs 108-103 in Game 5 on Monday night and took over the Western Conference Finals series lead 3-2.

Russell Westbrook added 23 points and 12 assists for Oklahoma.

The Spurs who looked unbeatable during 20-win streak a week ago, have now lost three straight and are on the verge of a stunning collapse.

Manu Ginobili scored 34 points, dished out seven assists and have six rebounds in his return to the starting lineup.

But trailing 106-103 and the Spurs down to their last shot, Ginobili missed an off-balance 3-pointer in the final seconds.

James Harden hit the biggest shot, draining a 3-pointer with 28.8 seconds left that pushed Oklahoma City's lead to five. He admitted afterward that the ball was supposed to go to Durant but had no choice but to let go with the shot clock winding down and Spurs rookie Kawhi Leonard in his face.

"The shot clock was running down and I had to make a play," Harden said. "Leonard was playing great defense on me. I just shot it with confidence. West Conference Finals -- that's a big shot."

Tony Parker had 20 points and Tim Duncan had 18 points and 12 rebounds for the Spurs.

San Antonio must win two straight games to avoid seeing perhaps their last best chance to win a title in the Duncan era end.

"Championship teams win on the road," Spurs coach Gregg Popovich said. "Oklahoma City just did that."

The switch wasn't announced until after Popovich met with reporters, with whom he refused to discuss any possible lineup changes. But pulling this big an adjustment this deep in the season likely didn't come easy for the NBA coach of the year.

The gambit drew mixed results. It looked like a no-brainer with Ginobili leading all scorers at halftime with 14, but new rotations for the Spurs made for rocky possessions. None more so than in the second quarter, when the Spurs shot 38 percent and trailed by as much as 14 before coming back in the second half.

Ginobili finished 11-of-21, including 5-of-10 from beyond the arc.

Game 6 is Wednesday night in Oklahoma City, where the Spurs must win to keep their playoff hopes alive.

(AP Photo/Darren Abate)