The two were together Chelsea where they enjoyed several trophy-laden seasons, but now prepare to face off when the La Liga champions host Galatasaray in the first leg of the Champions League quarter-finals on Wednesday.
Mourinho also managed Wesley Sneijder at Inter Milan, and he is looking forward to catching up with both players.
"I don't say Didier was the greatest player I have worked with because I have had so many great players," Mourinho told The Guardian. "But he was a great player, a great friend and somebody who will be part of my life forever. He would say the exact same about me. We created the kind of emotional links that are more than football.
"They were my players, we love each other and we respect each other. But we have completely conflicting objectives. They want to win and I want to win. I have to make help my players to make sure that they do not have a great game.
"They are two great players in my career, two important players. But now they are not my players – they are my friends."
Real Madrid meet Galatasaray at the Santiago Bernabeu on Wednesday.