The Foxes welcome Roma for the first leg on Thursday.
It is Mourinho's first game back in England since being sacked by Tottenham last year.
Rodgers, who worked with Mourinho at Chelsea, said: "He has nothing to prove to anyone. He will always be a winner. I cannot speak any higher of him. He is one of the greats of our generation.
"He had the X-Factor. There wasn't one single thing. He was brilliant in so many aspects of the game. Detail orientated, man management of the players, his understanding of the tactical adaptation of the game, he had that special quality I was able to see.
"I have got nothing but admiration for him. I became a manager in my own right but I will never forget what I gained from him as a young coach. I studied him and watched him and at that time it was a really special period."