updated 11:17 a.m. ET July 7, 2008

AMSTERDAM, Netherlands - Manchester United winger Cristiano Ronaldo had surgery Monday on his right ankle, and the Premier League team says it will know in a month when he'll be able to return.

The Portuguese star could miss the start of the season next month. He revealed after last month's European Championship he had been playing in pain the last three months.

Ronaldo arrived at the hospital Sunday night. He is expected to leave the Academic Medical Center on Tuesday, hospital spokesman Johan Kortenray told The Associated Press.

"The initial indications are that the procedure was successful,'' United said in a statement. "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.''

Ronaldo scored 42 goals for Man United last season, powering them to them to triumphs in the Premier League and Champions League. But at Euro 2008, Portugal was ousted in the quarterfinals.

The ankle surgery comes amid speculation of a possible move to Real Madrid. Madrid president Ramon Calderon said Sunday he is ready to begin transfer talks with Manchester United, but is not confident about signing the winger even if Manchester United consents.

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