Manchester United may yet kick off next season without Cristiano Ronaldo - but the club insist it will not be because he is being sold to Real Madrid.

The Portugal winger is expected to undergo ankle surgery next week, which could rule him out for six weeks.

Confirmation of Ronaldo's operation comes after the view of a specialist backed up that of medical staff from both United and the Portuguese Football Association.

The news came on the day United were forced to rubbish fresh reports from Spain that the 23-year-old will sign for Real, the latest claiming he will move within a matter of days.

A club spokesman said: "It is utter nonsense and totally laughable. Cristiano Ronaldo is not for sale."

Despite Ronaldo's desire to move and a huge fee of around £70million being on offer, United chiefs believe selling the player would cause huge disruption to the club.

Apart from the effect on the team's playing style and formation, it would also send a signal United are in some way a lesser team than Real.

The Glazer family bought United because they viewed it as the biggest club in the world so they cannot afford to been seen as weaker than Real Madrid, one of their biggest European rivals, or in thrall to their star player.

The message chief executive David Gill has given to the Glazers is if they stand firm on Ronaldo and neither sell him nor give him another big new contract then it will strike a major blow against player-power and have long-term future benefits for the club.

There is no real financial incentive to the Glazers either - the club's profits are already covering their debt repayments easily so there is no requirement to raise new capital.

If they considered selling Ronaldo, United manager Sir Alex Ferguson would argue he would need all the £70million fee as transfer funds to replace his most valuable player.