Ronaldo is now coached by Mourinho, the man many people predict will eventually succeed Sir Alex.
So who does Ronaldo rate as the best boss in the world?
He said: “You can’t tell the difference. They are incomparable. They have different ideas, different opinions. For me they are both the best in the world.
“I worked with Sir Alex for a few years and I know he deserves everything that he has achieved in his career. He works so hard, he is clever, he has experience, he is a human guy.
“Mourinho is similar, but he is younger. I have worked for a while with Mourinho now too so I’m entitled to say they are both very special. It’s not just Mourinho who’s special. They’re both special! This is why I like them both so much.”