The win also ranked as the franchise's third-largest comeback victory under coach Gregg Popovich.
"It was a fine win," Popovich said. "The guys really dug deep, pounded the rock. We kept a great attitude, and they just kept their minds on playing basic basketball and things turned their way. The effort was great, and they played a lot smarter in the second half. They took care of the ball, and just showed a lot of courage. Overall, a great team win."
San Antonio trailed by 23 points with 9:28 remaining in the first half (43-20) in large part due to a disastrous opening quarter in which the Spurs turned over the ball seven times while knocking down just six field goals. Veteran Manu Ginobili committed four of those turnovers as San Antonio connected on just 6 of 19 from the floor.
But sympathy never set in for a shorthanded Spurs squad down 23 points against an Oklahoma City Thunder team featuring a trio of bona fide stars in Carmelo Anthony, Paul George and reigning MVP Russell Westbrook.
"Pop doesn't let you feel sorry for yourself," said power forward LaMarcus Aldridge, who scored a game-high 26 points, including a putback off a Danny Green miss with 24.2 seconds remaining to help San Antonio preserve the win.
The 23-point margin was equal to that of the Cavaliers' comeback win over the Knicks on Monday.
At the conclusion of Friday's contest, Popovich told ESPN's Doris Burke that the team experienced "an attitude change from 'poor me' to 'screw you.'"
Green certainly served as a catalyst in the effort. Although the injured Leonard receives most of the recognition as San Antonio's best defender, Green is coming off a 2016-17 season in which he was selected to the NBA's all-defensive second team. He looked the part defending Westbrook.
Westbrook hit his first two shots of the night, but connected on just 3 of his final 20 attempts, including 1 of 10 when guarded by Green.
"It was a big one for us, a gutsy one," Green said. "We grinded it out and came back. So it was a lot of fun. Those games are always a good challenge. We came into the league to play in those types of games."
The Spurs started off the second quarter trailing by 14 points, and cut that deficit to 7 by halftime. San Antonio finally tied the game at 78 with 38.3 seconds left in the third quarter on a 27-foot jumper by Davis Bertans off a Dejounte Murray assist.
"They just came back," Westbrook said. "They played faster, and did a good job of getting themselves back in the game."
A Ginobili 3-pointer to start off the fourth quarter gave San Antonio its first lead (81-78) since Green put the Spurs ahead 2-0 just five seconds into the game when they secured the opening tip.
The Thunder trio of Westbrook, Anthony and George started off hitting 8 of 16 in the opening quarter. From the second quarter on, they combined to connect on 11 of 39, and contributed a total of 24 points in the second half.
Meanwhile, San Antonio's threesome of Aldridge, Pau Gasol and Ginobili came together for 30 on 8-of-13 shooting in the second half.
"It takes one, two, plays; three in a row," Gasol said. "But you've got to start somewhere to turn it around. We knew there was a lot of ballgame to be played. So we had still a margin to get back into the game, give ourselves a chance. I think the team showed a lot of heart, a lot of character tonight by not giving up. We fought and we got rewarded."
ESPN Stats and Information contributed to this report.
Pop gives succinct answer regarding Spurs' turnaround
Before the fourth quarter, Spurs coach Gregg Popovich says that the team changed their attitude from "poor me to screw you."