The table-topping Blues have dropped just two points from their opening eight Premier League matches and continued their fine early-season form with a 4-2 win over Tottenham Hotspur on Saturday, with Mata scoring twice.
While Di Matteo, who also won the Champions League and FA Cup double at Stamford Bridge last season, has been quick to play down his own role in Chelsea's success, Mata has heaped praise upon the Italian for his impact on the club's impressive performances.
"Robbie knows very well the team, Robbie knows very well the club as well. He is a legend here," said the Spanish international.
"And now, as a manager, he connects very well with the team, in every meeting, in every speech, he goes deep inside every one of us, talking about every game. I think it's very important to be ready for every competition, for the Premier League and now for the Champions League.
"He knows how important it is for the club to play these kinds of games, to win again the Champions League like last season. So, I think for us, he's the perfect manager."
Chelsea travel to Ukrainian side Shakhtar Donetsk in the Champions League on Tuesday evening.