Di Matteo led the Blues to an historic Champions League and FA Cup double last season after taking over from André Villas-Boas in March.
Mata has been in sublime form for the west Londoners this season, with his string of impressive displays earning him the Premier League player of the month award for October.
And the Spaniard has revealed that Di Matteo knows how to get the best out of his players even when they are not performing.
“His speeches in team meetings are very clever. And it’s true that he knows how to go into each player. He talks with each of us about our rivals and how important it is to win trophies for this club,” Mata told the Daily Mirror.
“With me, he always gave me confidence. Of course, when you are playing well you don’t need that.
“But when you are in a bad moment, you do need it, and Robbie knows when he has to say something and always gave that to me.”
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