Portugal are sweating over the fitness of their key playmaker and captain Cristiano Ronaldo with the World Cup in Brazil looming.
The World Player of the Player has been left out of what is arguably Real Madrid's toughest La Liga fixture until the end of the season because of a knee injury.
If the knee injury persists it could damage his chances of playing at the 2014 World Cup in June, which could be welcoming news for Ghana fans.
The Portuguese forward will sit out Los Blancos' trip to San Sebastian to face Real Sociedad on Saturday night, with Madrid needing maximum points to keep pace with leader Atletico and second-place Barcelona in the title race.
Ronaldo has been complaining of a slight knee injury in recent weeks and a decision has been made for him not to feature against the Basque club after a meeting between the player and manager this week.
In Wednesday night's 3-0 victory over Borussia Dortmund in the first leg of the Champions League quarter-final, Ronaldo left the field 10 minutes from the end after holding his knee while on the Bernabeu surface.
Ancelotti has repeatedly said the knee injury has not been an issue, but a decision to keep him out of the trip to Anoeta to face what may be Madrid’s toughest remaining fixture indicates otherwise.
"We're going to give Cristiano a rest; he's weary," Ancelotti told the gathered media before his side's weekend match.
"We're doing this to avoid any risks. There are a lot of important games ahead of us and we prefer him to sit this one out. He can train tomorrow and Sunday to be ready for Tuesday's game."
Madrid will go into the game without the Ballon d'Or winner and the league's top scorer.
Los Blancos' biggest asset this season has been their strength-in-depth and now, more than any other point this term, that will be tested.