Dynamic guard Westbrook contributed a game-high 40 points and 10 assists while league MVP Durant weighed in with 31 points on 11-of-22 shooting as the second-seeded Thunder evened up the best-of-seven series at 2-2.
The top-seeded Spurs, aiming for a return to the NBA Finals after losing to the Miami Heat in five games last year, were outshot by 49 percent to 40 from the field.
Point guard Tony Parker and Boris Diaw, off the bench, led the way for San Antonio with 14 points each but veteran All-Star forward Tim Duncan was held to just nine points on three-of-eight shooting.
"I think I did all right," a smiling Westbrook told Turner Network Television in a courtside interview after a stellar display that also included five steals. "Coming out with a win is most important.
"I just try to come out and give maximum effort. My team mates ask that of me and that's what I was trying to do at both ends of the floor."
Spurs coach Gregg Popovich applauded the performances produced by Westbrook and Durant, but felt his team had paid the price for not being aggressive enough.
"I thought they (Westbrook and Durant) did a great job," he said. "They are great players, and that's what they do. I was disappointed in our physicality."
San Antonio made a fast start, Kawhi Leonard pouring in two three-pointers to help his team race ahead 8-0 but Westbrook sparked an Oklahoma City fightback and they ended the first quarter on a 13-2 run to lead 26-20.
Durant then put on a spectacular show for his fans with a dazzling array of shots from all around the court, totalling 15 points in the second quarter as the faster-paced Thunder stretched their advantage to 58-43 at half-time.
San Antonio's second unit went on a rousing 18-5 run late in the third quarter but Oklahoma City maintained overall control and led 83-67 heading into the fourth.
There was no way back from there for the Spurs, despite continued good play from their reserves, and they ended the night by slipping to their ninth straight loss to the Thunder at Chesapeake Energy Arena.
"I thought the last two games we played as a group," Thunder coach Scott Brooks said after his team rebounded from two demoralising road losses to level the series. "Russell's defensive toughness really set the tone in this game tonight."
The series shifts back to San Antonio for Game Five on Thursday with the eventual winners advancing to meet either the Heat or Indiana Pacers for the NBA title.
"We've got to make it travel," Westbrook said of the need for Oklahoma City to take their winning form at home on the road. "We've got to win one there if we want to win the series.
"We've got to go there with the same mindset as tonight and try to come up with a win."
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