Manu Ginobili scored 26 points and the San Antonio Spurs turned it on in the fourth quarter to beat Oklahoma City 101-98 in the first game of the NBA Western Conference Finals.
The Spurs stretched their winning streak to 19 games and moved one game closer to booking their berth in the NBA Finals.
The winner of this best-of-seven series will face either the Miami Heat or Boston Celtics for the NBA title. San Antonio host game two on Tuesday.
The Spurs trailed by nine points going into the fourth quarter, when they turned the tables and out-scored the Thunder 39-27.
Kevin Durant led Oklahoma City with 27 points and Russell Westbrook added 17, but they just could not stop the Spurs in the final period.
"It was a hard-fought ball game," said Thunder coach Scott Brooks. "Nothing to be ashamed of.
"They're playing the best basketball in the league," Brooks said of San Antonio. "And we were right there."
Point guard Tony Parker scored 18 points with six assists for San Antonio, while Tim Duncan scored 16 and grabbed 11 rebounds.
With Argentine Ginobili leading the way, the Spurs bench contributed 52 points.
The Thunder closed the third quarter on a 10-3 scoring run to take a 71-62 lead.
Spurs coach Gregg Popovich was caught by video cameras exhorting his players to get "nasty".
"I said that? In the heat of the game sometimes stuff comes out of my mouth and it's embarrassing," Popovich said.
"I thought that we were playing for most of the first half and even the beginning of the third quarter a bit unconfidently, a bit on our heels, a bit unsure of ourselves.
"So I talked to them about they've got to get a little bit uglier, a little bit nasty, play with a little more fiber -- meaning you've got to take it to these guys, you've got to drive it, you've got to shoot it, you can't hold it," the coach said.
"We needed to be active and aggressive -- and we got that way in the fourth quarter."
"He just wanted to make sure we played with more energy," Parker said of Popovich. "They were playing with a lot more energy than us in the third quarter, and we were hesitating a little bit."
Parker's jump shot tied it at 73-73 early in the fourth as the Spurs delivered an 18-3 scoring run that put them up 82-76.
From there the Thunder did not get closer than four points, until James Harden drained a three-pointer as time expired to narrow the final margin.
Ginobili made 9 of 14 shots, including three of his five three-point attempts. In the fourth quarter he made all three of his shots from the floor and all five of his free-throws.
"That's Manu's game," Popovich said. "He's a scorer. That's what he's done for us his whole career. Without that, we have a tough time winning."
But Parker said the Spurs -- who were playing their first game in a week after completing their second-round sweep of the Los Angeles Clippers last Sunday -- would have to improve to hold off the Thunder.
"Oklahoma, they're a very, very good team," Parker said. "I think we're going to have to play a lot better if we want to win game two. If we play the same way we're not going to win game two."