Luka Modric will be out for three to five weeks due to an adductor injury.
"Modric felt pain in his adductor and will undergo tests in Madrid to determine the extent of the knock. We will know more on Monday or Tuesday," Croatia coach Niko Kovac told HTV.
Modric has been a key figure for Madrid in the opening months of the 2014-15 campaign, making 17 appearances in all competitions.
The absence of Modric could see Sami Khedira return to the Madrid starting XI in the next few weeks.