The Blues star is full of praise for the Portuguese, who is set to return to the club this summer, saying that his team-mates have fond memories of him
Goal exclusively revealed that the Portuguese coach, who spent three years with the west London club before being dismissed by Roman Abramovich in 2007, has agreed to return and replace interim boss Rafael Benitez in the summer.
Mourinho has fallen out of favour at the Bernabeu after surrendering the Liga title to fierce rivals Barcelona, as well as being dumped out of the Champions League by Borussia Dortmund at the semi-final stage.
Blues star Mata, however, was full of praise for the 50-year-old and suggests that his appointment will be well received by his team-mates at Stamford Bridge.
He told Sky Sports News: "Talking about Jose, for sure he's a great manager. I mean, he won everything almost in every country. He was in Italy, in Portugal here in England, and I think the players we have now for example in the dressing room have very good memories about him.
"And in Madrid I think the same. He's done a good job, Real Madrid is one of the best teams in the world, he is one of the best managers.
"We don't really know what is going to happen, but for sure - and that's a fact - he is one of the best managers in the world."