Manchester United's hopes of keeping Cristiano Ronaldo have received a boost after FIFA warned Real Madrid they will pay the consequences if they encourage the winger to break his contract.

Real have been linked with a move for the Portugal international and such has been the nature of their interest that Manchester United, who are determined to keep him, made a formal complaint to the world governing body.

FIFA have ruled Real Madrid has no case to answer as yet, but are poised to take action should the winger be induced to breach his contract and have asked the Spanish Football Federation to remind them of their responsibilities.

A FIFA statement said: "The Spanish Football Federation has been informed of the complaint lodged by the English club and been asked to remind Real Madrid about the potential legal consequences of a breach of contract without just cause during the protected period and of a possible inducement to such a breach of contract."

Whether that will be enough for Manchester United to keep their star remains to be seen as fresh reports today have revealed Real Madrid are set to open negotiations over a £50m move.