United are thought to be lining up a £55m bid to bring Ronaldo back to Old Trafford this summer.
The complex deal will involve club sponsors Chevrolet or Nike helping to fund the Portuguese superstar's massive wages, in order to comply with UEFA's new Financial Fair Play rules, says the Daily Star.
But Real boss Mourinho has told Ronaldo "it would be good" for him to stay at the Spanish giants.
When asked about the importance of Real hanging onto their star player, Mourinho claimed "it would be fantastic for the club and vital".
"When you have a player with these characteristics, you have to do all that is possible not to lose him," he added.
"It's obvious that he can play wherever he wants to play.
"It would be good for Real Madrid as well as Ronaldo if he continued."
Can United convince Ronaldo to leave Real this summer? Give us your shout below...