The attacking midfielder feels the Portuguese trainer is arguably the best in the world and has hailed the Madrid coach's influence on his career
The Netherlands international worked with Mourinho at Inter in the 2009-10 campaign when they won Serie A, the Champions League and Coppa Italia, and Sneijder has nothing but praise for his former boss.
"Mourinho is like a second father to me. He is a powerhouse. In football we have powerhouses who are players, and ever since I met Mourinho, we can say that there are powerhouses who are coaches. And he certainly is, without any doubt at all," Sneijder told Marca.
"He is a very special person for me. As a coach he is incredible, No.1. It was he who gave me confidence, and I enjoyed playing football like never before. And as a person he reaches you much more than in his role as coach. Mourinho is a friend.
"It's not easy to explain. You have to be with him to find out just what he is like. The key to him is how he convinces you, how he helps you if things aren’t going well for you.
"He is on top of everything and always knows how to help a player, sometimes doing one thing, sometimes another, but whatever he does it is for the good of the club, the player and the person."
Wednesday's match at the Santiago Bernabeu is scheduled to kick off at 20:45CET.