The Dutch winger made very limited appearances since joining from Chelsea in the close season due to injuries.

"All this is simply motivated by anxiety. That's the problem we have with Robben," Schuster was quoted as saying by Real's website.

"He wants to play and prove that he's ready. That anxiety has played against him. It's nothing serious, but we have to control it."

Schuster revealed that Robben returned to training but will not catch Real's Primera Liga game against Osasuna on Sunday.

Argentinean defender Gabriel Heinze has been included in the squad after recovering from injury.