David Alaba has returned to Real Madrid from international duty with Austria nursing an injury and is now a doubt for the upcoming Champions League meeting with Shakhtar Donetsk and the Liga Clasico with Barcelona.
The versatile defender made two outings for his country during the latest break in domestic duties, with 180 minutes of game time in World Cup qualifying ties with Faroe Islands and Denmark.
He is now back in Spain and preparing to undergo tests in an effort to determine if any course of action needs to be taken.
Alaba, who joined Madrid as a free agent over the summer after reaching the end of his contract at Bayern Munich, is understood to have picked up a knee problem.
Medical examinations will be required in order to fully understand the severity of the problem, with those due to take place on Thursday.
