The game also had little effect on the standings: San Antonio is likely to finish second in the Western Conference and the Thunder are virtually locked into third. But the Thunder said it was important to maintain momentum.
Westbrook scored 20 points in the first half to help the Thunder take a 48-44 lead into the break.
Andre Roberson hit a 3-pointer, then Westbrook rebounded a missed free throw and found Steven Adams running down the middle of the lane for a dunk. Westbrook then set Ibaka up for a dunk to push Oklahoma City's lead to 69-56.
Westbrook uncorked a powerful one-handed jam to bump Oklahoma City's lead to 74-59 late in the third quarter. Durant scored nine points in the period to help the Thunder take an 83-63 edge into the fourth.
Spurs: Committed just two turnovers in the first quarter. ... Rookie C Boban Marjanovic had 13 points and six rebounds in his second start. ... Other than Danny Green, who has started every game this season, San Antonio's starters entered with a combined 13 starts this season. ... Shot just 38.6 percent in the first half. ... The Spurs dropped to 14-1 on the second game of back-to-backs this season. ... F Boris Diaw was called for a technical foul in the fourth quarter.
Thunder: Durant scored 20 or more points for the 68th straight game. ... The score of Oklahoma's 80-68 Elite Eight win over Oregon was shown on the big screen in the first quarter and drew a loud cheer. ... F Kyle Singler returned to action after missing three games with lower-back soreness. ... Westbrook was called for a technical foul in the third quarter.
Spurs: At Memphis on Monday night.
Thunder: At Toronto on Monday night.