Ivanovic put in match-winning performances both at Burnley last Monday and against Leicester at Stamford Bridge on Saturday, and the Blues boss says his player gives everything he wants from a full-back.
Mourinho described him as 'immense', saying: “There he was in the first game participating in goals, scoring goals.
“(Against Leicester) he had two big possibilities with two fantastic saves by (Kasper) Schmeichel.
“He is strong going forward, he is strong defensively. Obviously I expect this from him because he is one of the ones from our important days. Also by the mental point of view he belongs to the strong days, and he is being important.”
Asked if Ivanovic had always received the credit he deserved, Mourinho insisted the defender's selfless play did not rely on such plaudits.
“I don't know,” he said, “but I don't think he worries too much about it.
“Iva is about – 'Select me to play, give me the right back shirt, and everything is good'. So I don't think it is a problem.
“But so many years here, so many years he is performing at a high level. He is not the captain because, as you know, we have two or three guys older than him. But he is fantastic.”
After six and a half years on Chelsea's books, and at the age of 30, Mourinho said Ivanovic was taking on the mantle of the elder statesman, and showing a great example to some of the Blues' newer players.
“In this moment you could feel some of the lesser boys, at the beginning of the season, to play 90 minutes at that tempo is difficult,” said Mourinho.”
“Some of them were in trouble. And Iva, because his pre-season is so good, and he is so well prepared at the time, is one of these guys that can keep that strength and that stamina for the whole game.”
