Ronaldo calls Ferguson his footballing father.
Ronaldo revealed to The Sun: "I arrived at United aged just 18 years old and he taught me how to grow up properly in the football world.
"Who better? He has so much experience - 1,000 players have passed through his hands.
"So he knows and appreciates what young players need.
"And what he taught me was the importance of decision making.
"How important it is to make the right decisions on the pitch and off it.
"That's why I say he was like a father to me.
"He taught me everything, he helped me so much, guided me on so many important things.
"That was in football and in life because his influence and interest doesn't stop at the touchlines. He cares about you as an individual.
"He is a very human person who understands what you want and what you need.
"I remember one day in my first season and we came to Christmas and, of course, there is no winter break in England.
"I asked him: 'Coach can you give me three or four days to go home to Portugal?'
"And straight away he said: 'OK no problem.'
"He knew I was very important to the team but he also knew at that time I needed my family so much and that was a very important moment for me.
"I realised he understood and he cared.
"Sometimes when you asked him for something you didn't get an answer instantly.
"He would say: 'Let me think about it.' And then next day he would give you his answer - yes or no.
"Even if it was a 'no' there was a reason and an explanation.
"He knows how to treat people well, how to make you happy, how to motivate you.
"He has that in abundance and it works because it's real - it comes from inside him.
"So I owe him a lot. That's why I keep in touch and that's why it will be great to see him."