The 79-year-old Scot, who took Ronaldo to Old Trafford in 2003 in a £12.4m move from Sporting Lisbon, is understood to have spoken with the player on Friday morning when it seemed a move to rivals Manchester City was on the cards.
That was followed by an announcement late afternoon which read: “Manchester United is delighted to confirm that the club has reached agreement with Juventus for the transfer of Cristiano Ronaldo, subject to agreement of personal terms, visa and medical.
“Everyone at the club looks forward to welcoming Cristiano back to Manchester.”
According to the Manchester Evening News, the 36-year-old is set to sign a two-year contract worth £480,000-a-week after United owners, the Glazer family, sanctioned a late swoop for the five-times World Player of the Year, gazumping their city rivals in the process.
It is reported that United will pay Juventus a fee of £25m for the superstar who left the club to join Real Madrid for a then world record fee of £80m in 2009.
Man Utd boss Ole Gunnar Solskjaer hinted at the imminent arrival of his former teammate during his pre-match press conference on Friday morning.
"I didn't think Cristiano was going to turn out leaving Juventus," he said.
"It's been speculation this morning, speculation the last few days, of course. We've always had a good communication - I know Bruno (Fernandes) has been talking to him as well. He knows what we feel about him and if he was ever going to move away from Juventus, he knows that we're here.
"Cristiano has been a legend of this club, he is a legend of this club, he's the greatest player of all time, if you ask me. I was fortunate enough to play with him, I coached him (in 2008) when I got my job. He almost retired me in that Wolverhampton game (in 2003) when I got injured because he kept switching sides!
"He's such a tremendous human being as well, so let's see what happens with Cristiano. Everyone who has played with him, I think, has a soft spot for him."