It's been 13 years since Portuguese legend left Sporting CP for Manchester United, but the details on exactly how Sir Alex Ferguson managed to sign one of the most exciting players in the history of the game still carries huge intrigue.
Now at Real Madrid, the electric forward spent six years at Manchester United, winning three Premier League titles, one FA Cup, two League Cups and the Champions League.
He has added two Champions League winners' medals to his collection since moving to Spain, but it was at United that he shot to fame.
So how did it all go down? Well Ronaldo himself has spoken, revealing exactly what happened, speaking atthe launch of the Nike Mercurial CR7 Chapter 3 in Lisbon (Mirror).
The forward, along with Portugal manager Fernando Santos and former teammate Rio Ferdinand, explained what transpired on that night in 2003,when United played Sporting in Lisbon.
Santos has recently lamented on the fact that he put his boy wonder on show for Sir Alex, but claimed that he did not expect things to happen as quickly as they did.
Ronaldo himself, had no idea the move could even happen.
"My friend says to me, 'Cristiano - if you play well against Manchester United, you can go to play there'," said Ronaldo, who had an amazing performance that night.
"I said, 'Are you kidding me? No, it's too early. I'm 17!'
"Then that night, I played unbelievable! I played so good!"
Ferdinand then jumped in to tell the story from his vantage point, claiming that he asked the former manager to sign the attacker, but Sir Alex was already on it.
"I remember speaking to the manager and saying, 'Are we going to get this guy? Who is he? He said, 'Listen, I'm working on it. Don't worry¦'
"We were waiting for one and a half hours after the game. Then the manager comes back in and said, "I think I've got him.'"
"Man United and Sporting Lisbon came together for this game, and we went home with their baby. It was a good trip!"
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