The former Arsenal captain agreed to join the club from Barcelona earlier this month and his new manager has backed the 27-year-old to make an impact at Stamford Bridge.
Chelsea paid close to 35 million euros to acquire the services of the former Arsenal captain, who spent eight years with the Blues' north London rival.
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Mourinho believes his experience in the Premier League will stand him in good stead when he joins up with Chelsea's squad.
“He is the kind of player we need,” the Portuguese told ITV. “Not just for his qualities as a player but also his competitive personality.
“He is a player in the best years of his career – 26, 27, 28. He knows England well, he knows the Premiership well, so he will not need time to adapt. I think he is the kind of player who will come and train for a couple of weeks and be ready to prove himself.”
Fabregas is likely to replace Frank Lampard in the Chelsea starting XI, with the England midfielder set to leave the club after the World Cup in Brazil.
New York City FC is reportedly the front runner to sign the 36-year-old, with QPR also credited with an interest.