According to reports in Sportsmail, the La Liga club's president Florentino Perez has been forced to consider offers for the player.
Real Madrid splashed out £80 million to Manchester United to prise him from England in 2009, and Perez has admitted that he would expect to make a significant profit in order to keep fans happy, despite the sale of the star.
The question is, who can afford Ronaldo? Given his annual wage bill of 20 million euros, it would take a weekly wage of over £300,000 for any Premier League club to acquire his services.
Further reports indicate that there have been long-standing issues between the Portuguese duo for a while, especially over the ex-Chelsea manager's tactics during their UEFA Champions League semi-final losses against Barcelona.
Ronaldo was displeased with Mourinho's system, saying: "I don't like it, but I have to adapt because that is the way it is," and found himself immediately dropped for Real Madrid's next fixture against Real Zaragoza.
It was earlier reported that Premier League big spenders Manchester City could consider a move for the Portuguese, and although manager Roberto Mancini has made light of such speculation, it is telling that he joked about signing Cristiano Ronaldo on Friday.
"We have signed Cristiano Ronaldo for £200million", said the Italian.
He then explained his comment was tongue-in-cheek, but added: "Cristiano Ronaldo is a fantastic player but I don't think he will leave Real Madrid."
Time to pull out that cheque-book, Mancini?