De'Aaron Fox had 12 points, 10 rebounds and five assists for San Antonio, who have not lost three consecutive games all season. Stephon Castle and Devin Vassell added 13 points each.
Game 5 is Tuesday in Oklahoma City, followed by Game 6 on Thursday in San Antonio, both live on Sky Sports.
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"You definitely don't want to go down 3-1 going into their house," Vassell, of the Spurs, said after the game. "We knew we had to respond and that's how you respond. You get stops.
"You don't try and focus on the offensive end, you get stops, you get out of transition. You guard your yard and that's what we did."
Shai Gilgeous-Alexander had 19 points on 6-for-15 shooting for the Thunder.
Wembanyama took Oklahoma City's 123-108 victory Friday in Game 3 personally. The 7-foot-4 star from France said he needed to be better to make his teammates better. He was monumentally better Sunday night - and so was San Antonio.
"We all have high standards and I know I have a lot of responsibilities, but I'm here for it," Wembanyama said. "Yeah, it was better today. It wasn't perfect. But, you know, all of us, I'm talking about the whole organisation, so we're going to have to do things that we didn't sign up for."
The Spurs limited the Thunder to 33 per cent shooting from the field, including 6 for 33 on 3-pointers (18 per cent).
After being outscored 76-23 in bench points in Game 3, San Antonio's reserves scored 30 points while limiting Oklahoma City to 34.
The Spurs had another hot start in Game 4 after opening the previous game on a 15-0 run. Unlike Friday's lopsided loss, the Spurs never relinquished their lead this time around.
San Antonio had an assist on all 10 field goals in the first quarter.
San Antonio held Oklahoma City to 38 points in the first half, tied for its second-lowest half in the past four regular and postseasons. The Thunder are 2-9 when they score less than 40 points in any half over the last five seasons.
Oklahoma City's franchise low is 65 points in a playoff loss to Memphis on May 3, 2014, and its second-fewest points had been 85 against San Antonio on May 21, 2014.
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