Sergio Ramos is likely to miss three games after Real Madrid confirmed on Thursday the defender has sustained a hamstring injury.
Ramos came off towards the end of the first half of Spain's 6-0 victory over Germany in the Nations League on Tuesday.
He is expected to be out for 10 days, which would mean Madrid being without their captain for their Champions League group game away at Inter Milan, as well as La Liga matches against Villarreal on Saturday and Alaves.
It represents a significant blow for Madrid, who could also be without Raphael Varane away at Villarreal this weekend.
The club have confirmed Varane is struggling with a shoulder problem and will have to be assessed on Friday.
Zinedine Zidane may have to turn to Nacho Fernandez in defence and Eder Militao, who has tested negative for coronavirus.
Eden Hazard has also returned a negative test, meaning the Belgian will also be available to play at La Ceramica.
Karim Benzema returned to training on Thursday after a groin strain.
Real Madrid will be hoping to bounce back this weekend after a 4-1 defeat by Valencia before the international break.