The Barclays Premier League champions will first be without the Belgium goalkeeper for Saturday's match at Everton after Courtois suffered the injury in training.

"Courtois was injured in a training session with the goalkeepers and I cannot tell you much, but I can tell you that he needs surgery in his right knee," Mourinho said.

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"As a consequence of that he will be out for quite a long time. I cannot be at this moment more specific about the injury or the time he will be out."

It is another blow for the Blues, who have four points from their opening four games and sit eight points behind leaders Manchester City.

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