The 25-year-old midfielder has signed a five-and-a-half year contract with the west London club, whom he left to join Benfica three years ago.
“We [him and Mourinho] have spoken. He said to be professional, to give my best for the team,” Matic told Chelsea’s website.
He has grown as a player in Portugal and has become a fantastic all-round midfielder
“It’s exciting to work with him, he is the best coach in the world and I want to work with him for a long time. I am ready.”
Mourinho added: “He has grown as a player in Portugal and has become a fantastic all-round midfielder.
“I am sure he will become a very important member of the squad and help us to achieve our ambitions.”
The Serb, who is cup-tied in this season’s Champions League, moved to Benfica in January 2011 as a makeweight in the deal to bring defender David Luiz to Stamford Bridge.
“I want to play and help the team to win the Premier League, and if it’s possible to play in and win the Champions League in the future. I want to win titles here,” Matic continued.
“I’ve played regularly in a big club at Benfica, where it is not easy and there is a lot of pressure.
“In those years I learned to be a winner and play under that pressure. I developed tactically in Portugal also, training very hard and I believe I am better physically also.”
Matic played in all but one of Benfica’s games as they reached last season’s Europa League final, where they were beaten by Chelsea in Amsterdam.
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