Ronaldo blow for United

(GETTY IMAGES)

Cristiano Ronaldo will miss the start of the new season after undergoing surgery on his right ankle.

Manchester United, who have had to fend off a new verbal claim for Ronaldo's services by Real Madrid president Ramon Calderon today, said the operation in Holland had been a success.

However, it will be at least a month before Professor Niek van Dijk, the Dutch ankle specialist who operated on the 23-year-old, can assess when he will be ready to return to action.

Van Dijk is one of the world's foremost experts in ankle injuries, and is a former head of Dutch Squash Federation's medical committee. He operated on the Portuguese winger at the Academic Medical Centre in Amsterdam.

United said in a statement afterwards: "Cristiano Ronaldo underwent surgery today to his right ankle and the initial indications are that the procedure was successful.

"Cristiano will begin his convalescence under the direction of club medical staff and an estimation of his return to full fitness will be possible following review by the specialist in one month."

It remains to be seen whether the operation has any adverse effect on Real Madrid's continued pursuit of Ronaldo - certainly the Spanish club know all about the injury and show no sign of backing away despite United's refusal to entertain a £70million transfer.

Calderon's latest remarks have infuriated United after he said they should be "happy and proud" to let Ronaldo leave the club in "the transfer of the century".

He said: "I think that, first of all, it's the desire of the player (to join us), but, of course, Manchester shouldn't be angry and they should open up their stance.

"We can't be blamed if nearly every player wants to come to Real Madrid. If I was Manchester United I'd be happy and proud to be able to negotiate such a transfer for one of my players.

"Everything would be a lot easier if United realised that they could pull off the transfer of the century."

Calderon appeared confident a deal could still be reached, as he believes that if a player wants to leave then there is little a club can do to stop him.

But he again insisted the Spanish champions would not act on their interest until United agreed to talks.

Calderon continued: "It depends on the player, on Ronaldo. Since I've known football it has been the case that the desires of the footballer are what decide matters.

"If Ronaldo wants to leave Manchester, he'll leave. If he wants to stay, he'll stay.

"I don't think you can keep anyone in a place where they don't want to be, not even in a family.

"But I insist that for a formal negotiation to start Manchester United will have to open their doors to us. Manchester have to want to talk."

On Ronaldo's ankle injury Calderon added: "At the moment that is something which should only concern the player and United."

United are, however, resigned to losing Sir Alex Ferguson's assistant Carlos Queiroz, who is set to become head coach of the Portugal national side.

Swansea chairman Huw Jenkins has denied his club's manager Roberto Martinez is in the running to succeed Queiroz, while Barnsley manager Simon Davey has played down reports linking with the job.