Lisbon: Cristiano Ronaldo is expected to have an operation on his right ankle early next week.

A consultation with a Manchester United-appointed specialist resulted in the Premier League champions being informed that surgery was required to resolve the player's long-standing injury.

The 23-year-old Portugal international, on holiday after Euro 2008, was examined by a specialist flown out by United to assess the damage to the ankle that has proved problematic since March.

Its condition has deteriorated with the player's involvement in the European Championships, which saw disappointment as Portugal went out in the quarterfinals.

United's club doctor, Steve McNally, and his counterpart from the Portuguese Football Federation, met the player in Lisbon on Wednesday in an attempt to resolve the problem that has troubled Ronaldo since March.

Specialist's verdict

United delayed a decision until receiving the verdict of a specialist, who formed the same opinion that an operation would be the quickest route to curing the problem and restoring Ronaldo to full fitness.

United have yet to decide whether Ronaldo must return to Manchester for the operation or allow him to go under the knife in Portugal.

But the double Footballer of the Year, who has still to play down talk of a summer move to Real Madrid, is facing at least four weeks on the sidelines as a result of the surgery.

With his rehabilitation from surgery delaying his return to pre-season training, originally scheduled for July 14, United fear that he could be out of action until early September.

Such an absence would rule him out of the club's entire pre-season, which begins at Aberdeen next Saturday, plus the opening fixtures of the Premier League season and the Uefa Super Cup clash against Zenit St Petersburg in Monaco on Aug 29.

With international fixtures pencilled in for the start of September, Ronaldo's first appearance of the season for United could come in the Premier League visit to Liverpool on Sept 13 - a week before the trip to Chelsea.