Real Madrid midfielder Toni Kroos is struggling to make their Champions League clash with PSG.
Cadena Copa says Kroos is suffering a muscular issue.
The German missed training this Thursday and is going for further tests, but it doesn't look good.
Kroos is almost certainly ruled out against Real Sociedad on Saturday night, while he is also a doubt for the Paris Saint-Germain return leg at the Estadio Santiago Bernabeu next Wednesday.
If the German isn't able to play against the Ligue 1 leaders, that is an especially significant blow for Los Blancos because Casemiro is also suspended for that game.
Ancelotti had already suggested that Kroos could play the Casemiro role, with Fede Valverde and Luka Modric flanking him, but now the Italian might have to look for alternative solutions, such as Eduardo Camavinga.