The 28-year-old has been angered by the Spanish club's refusal to negotiate a new and improved deal to extend his stay at the Santiago Bernabeu.
Ronaldo's current contract has a clause written into it, which sees Real Madrid rake in 40 per cent of his personal endorsements.
But, given the fact that the Portuguese international is one of the biggest stars in world football, he effectively pays more out of his own pocket than he receives from the capital club in wages.
Real Madrid's refusal to change their stance has led to rumours Ronaldo could make a sensational return to former club Manchester United, with Sir Alex Ferguson ready to splash £55million to bring him back to Old Trafford.
In order to make the deal possible, Manchester United's chief sponsors Chevrolet are ready to make the Real Madrid forward a global brand ambassador, with the Premier League giants set to offer Ronaldo £200,000-a-week in wages.
Four years after he left England in a club-record £80million deal, Ronaldo could return to these shores at the end of the season, in what would be regarded as one of the most celebrated transfer comebacks in the Premier League era.