French superstar Wembanyama was ruled out of the remainder of the game after stumbling and banging his head on the hardwood following a collision with Portland's Jrue Holiday.
Wembanyama looked dazed as he lay on the floor before slowly getting to his feet and jogging off court to the locker room.
The Spurs later confirmed Wembanyama had entered the concussion protocol and would play no further part in game two of the Western Conference playoff clash.
The injury to the 22-year-old occurred just a day after he was named the NBA's defensive player of the year.
Wembanyama scored 35 points in San Antonio's game one victory over Portland on Sunday.