The 24-year-old signed for Sir Alex Ferguson's side from Sporting Lisbon in August 2003 for £12.24 million, a bargain for a player who went on to bag 46 goals in all competitions in 2007/08, winning the Premier League, Champions League and FIFA World Player of the Year titles.
But all the above could so easily have not taken place, with the Portuguese admitting he held talks with Inter over a potential move to the San Siro while he was still plying his trade in his home country.
"It has been many years and I don't remember too well," he told Corriere dello Sport. "When I was 17 or 18 there was interest and someone spoke to me about the possibility of coming to Italy.
"I don't remember what they told me because many years have passed, but it was a thing which we discussed. Then I arrived in Manchester and I came here."
The two sides meet again at Old Trafford on March 11 locked at 0-0 following a stalemate at the San Siro largely dominated by United, although they could not convert their superiority into a crucial away goal.
However, Ronaldo remains confident the Red Devils can see off Jose Mourinho's side on home soil, despite failing to net in Italy.
"In the first half we played in a really good way and I'm surprised to have not won because we did better than Inter," he said.
"We had more opportunities to score and we have been unlucky too. I'm still a little angry because we have not won but anyway we put in a fantastic performance and I'm proud to be a part of a side like Manchester.
"We will have new opportunities to score and this time we won't be wrong. I assure you. We will have our supporters and better faith.
"We will respect Inter because they are a strong side, but we don't fear them. The aim is to play as in the first-half in the San Siro. Should we do this, I'm sure the final result will be different.
"I'm confident. Considering the team we have, we can do it. I want to lift the Champions League again."
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