City were offered the chance to sign the 36-year-old but although a move was considered, they have decided not to move forward.
Manchester United manager Ole Gunnar Solskjaer hinted that the club could make a move for Ronaldo at his news conference on Friday afternoon and sources have told ESPN that after being made aware of United's late interest, it was communicated to Juventus that Ronaldo wanted to return to Old Trafford and that he asked the Serie A side to open negotiations. Ronaldo left United for Real Madrid in an £80 million deal in 2009.
Swap deals with United players moving to Turin have been discussed but sources have told ESPN United are now prepared to pay Juventus' €28m valuation. Plans are in place for Ronaldo to undergo a medical in Lisbon this weekend, provided the two clubs can come to an agreement. Ronaldo left Italy on a private jet on Friday. Sources have told ESPN that United are "confident" they can get the deal over the line and that talks are now "advanced".
Juventus manager Massimiliano Allegri confirmed on Friday that Ronaldo wanted to leave the club before the transfer window deadline on Aug. 31.
Sources said that City were tempted to explore the possibility of signing Ronaldo after Harry Kane announced he would be staying at Tottenham Hotspur and that the Portugal international was keen to move to the Etihad Stadium, before United's interest became known. City, according to sources, considered signing Ronaldo but decided it was not the right fit, particularly because of the finances involved.
ESPN has been told that Ronaldo was still exchanging texts and WhatsApp messages with some ex-players as late as 1 a.m. BST on Friday morning.
Wayne Rooney, who played alongside Ronaldo at United, spoke on Thursday to say he doubted that Ronaldo would risk his reputation at Old Trafford by signing for City.
And sources have told ESPN that Ronaldo was told in clear terms by former teammates that his standing in United's history, and the affection with which he is still held by the fans, would be damaged forever if he signed for City.
Information from ESPN's Mark Ogden was used in this report.