The 24-year-old, who cost Real £85.3million from Tottenham in September, suffered another setback on Wednesday as a thigh muscle complaint ruled him out of a 4-0 Champions League victory over FC Copenhagen.
Ancelotti told Real's official website: "We are not worried, he has not played because of muscle fatigue and it is nothing special.
"He is waiting to recover his optimal fitness. He was not at 100 per cent but he will get there because he has 15 days of rest and then will be ready.
"He is not happy and that is normal, he wants to play and is eager but it is not a problem. Now we have time to get him into a good physical condition and avoid injuries."
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