Wembanyama, who only returned from a calf injury earlier in December, landed awkwardly after jumping up for a rebound during the fourth quarter of the game in San Antonio.
The French prodigy stayed on the floor for several seconds before being helped off the court and hobbling to the locker room.
Wembanyama had scored 31 points with 13 rebounds before he departed.
However the French star later returned from the locker room to sit on the bench and celebrated with his teammates as they closed out a 134-132 victory.
Spurs head coach Mitch Johnson was unable to provide details on Wembanyama's injury but was heartened by the fact the Frenchman returned from the locker room at the end of the game.
"I've not been able to speak to the medical staff yet but you know I think I saw what everyone else saw," Johnson said.
"Obviously he finished the game on the bench with his teammates so I think that made me feel good.
"It was good to see him walk back out and be able to finish the game on the bench with his teammates."
Afterwards, Wembanyama said he had suffered a left knee hyper-extension which would require further examination, but revealed he felt confident of making a quick recovery.
"My body's feeling good, just sore," Wembanyama said. "I'm very confident, optimistic."
Wembanyama said he had even tried to re-enter the game in the fourth quarter.
"I was this close to coming back into the game but they had to hold me back," he said.
"It was just a hyper-extension. It should be minimal, whatever. We've got to do everything tomorrow just to check that everything's okay."
Wembanyama added that he hoped to be available for San Antonio's next game on Friday.
"I expect to be back next game - I don't know that (the team) expects," he said.