The Belgian was jeered during Tuesday’s disappointing 2-2 Champions League draw at home with Club Bruges as the visitors raced into a shock two-goal lead.
Real Madrid coach Zinedine Zidane defended under-fire goalkeeper Thibaut Courtois following criticism for his lacklustre start to the season.
The Belgian was jeered during Tuesday's disappointing 2-2 Champions League draw at home with Club Bruges as the visitors raced into a shock two-goal lead.
He was substituted at halftime with an issue that will keep him out of Saturday's top-of-the-table clash with second-placed Granada in La Liga.
In a statement on Friday, Real denied local media reports suggesting the Belgian had been diagnosed with anxiety.
The club said the player was suffering from 'acute gastroenteritis with dehydration and an electrolyte imbalance', an issue Zidane confirmed.
"He was feeling bad (before the game against Bruges), that I know for sure. These things can happen. He had an upset stomach but he was able to start but at the break he wasn't good," the Frenchman told a news conference.
Alphonse Areola, who replaced Courtois in midweek, will deputise.
"The important thing is how he feels. Of course he is not the main reason for what happened in the first half against Bruges. Yes, he's the goalkeeper, but he's not the sole culprit," Zidane said.
"Tomorrow we are playing in a game that's first versus second, so we aren't doing too badly. The fact it's first against second means a lot; they're a side that are having a good season, just like us, and of course we want to play our best. We've not had a lot of recovery time but we're ready."
Zidane is facing yet another injury crisis in defence ahead of the visit of the newly promoted side after confirming that left back Marcelo, who did not train, will be absent with a hamstring injury.
Already without injured duo Ferland Mendy and Nacho, who can deputise for the Brazilian, Zidane will have to improvise when it comes to team selection. However, he said he would not be pushing Gareth Bale back into the position where he started his career.
"To be honest that's not even entered my mind. No, not at all. But we have other options," he said.
Those include new signing Eder Militao, who has operated at right back in the past. "Yes, that's an option, especially because he's actually a defender," Zidane said. "He's played for us on the right-hand side and it's definitely an option."