Sir Alex Ferguson firmly believes Cristiano Ronaldos immediate future at United is secure, but he says future Reds success in Europe is vital to keeping the prodigious Portuguese winger at Old Trafford.

Ronaldo has four years left on his current contract, but Sir Alex admits a time will come when the player has a big decision to make over his future.

United clinched a dramatic third European Cup in Moscow on Wednesday and Sir Alex says improving that record even further will be a crucial point in persuading Ronaldo to extend his stay in Manchester even further.

Real Madrid continue to make the world aware of their interest in Ronaldos services with Real coach Bernd Schuster and president Ramon Calderon both expressing a desire to see the winger at The Bernabeu. But Sir Alex remains unflustered, as he should having just won a league and European Cup double.

You get used to it with Madrid, said the United boss on Friday. Schuster's talking and Calderon's talking. Real think they can ride roughshod over everyone, but they won't do it with us. They have no moral issues.

"In terms of great clubs, Barcelona have far better morality than Real Madrid will ever have. Real use this Marca newspaper as a vehicle to unsettle players.

"Do you not think we have had many expressions of interest about our players from big clubs in Europe? Real Madrid are not the only club interested in Ronaldo. But the others are not saying so. They don't get into this nonsense.

"The simple fact of the matter is that he has four years left on his contract and he is happy here.

Of course, the players you want to keep, you have to work hard to keep," added Sir Alex. "That is a fact in the modern era. He is 23, when he gets to 25 or 26 he will have a big decision to make. That will be our biggest task when he gets to that age.

Its about how big we become and how big we are then in terms of European trophies. That European success will resonate with him. Thats why I make the point about us striving to be better at winning European Cups."