Moggi has laid bare how Sir Alex Ferguson rushed through a deal for the Sporting CP starlet way back in 2003.
He recalled to Tuttosport: “In 2003, Mendes was looking to engineer a move for his first great player, Cristiano Ronaldo.
“He was a kid of 18 who had just made his debut for Sporting and (Jorge) Mendes wanted him to move to Italy.
“He was obviously talented but he was too young for them and they were not convinced.
"Juventus on the other hand said yes and sent us to Lisbon with Mendes to tie up the deal with Sporting."
However, Moggi reveals Fergie's son Jason was a key man in the deal.
“In a matter of half a day, he became a United player.
“It was a deal that could have changed the history of European football.
“I thought about it a million times during the days I was in Lisbon.
“Seeing his attitude and how he handled himself I think he could still have been a Juventus player today."