Kawhi Leonard has entered the league's concussion protocol and will not play in Saturday's game against the Golden State Warriors.
Leonard suffered an apparent head injury on Thursday night, late in the third quarter of the Spurs' 102-92 loss to the Oklahoma City Thunder.
"He got hit in the mouth or the cheek or the head or something. I'm not sure which. So the trainer thought he should sit," Popovich said.
The Spurs originally anticipated that Leonard would not go into the NBA's concussion protocol but changed course after performing additional evaluations.
Leonard's injury came during a contest that a few Spurs described as "chippy" due to the physicality between the teams throughout.