According to Real Madrid reporter Mario Cortegana from The Athletic, the club said Alaba's injury did not look good.
In the match against Villarreal, Alaba was substituted in the 35th minute of the first half with a knee injury, and Nacho came on in place.
Racing reporter Mario Cortegana reported that the club said Alaba's injury "doesn't look good" and that a scan will be carried out tonight or tomorrow.
In addition, left-back Ferran Mendy, who was substituted at half-time, felt discomfort in his right leg and will be checked tomorrow.
