Roberto Fabián Ayala (locally [ro'ße?to fa'ßjan a'?ala]; born 14 April 1973), nicknamed El Ratón (English: "The Mouse"), is an Argentine former footballer who played as a centre back for the Argentina national football team, as well as Valencia and Real Zaragoza in Spain, Milan and Napoli in Italy and River Plate in his native Argentina.
Regarded as one of the best central defenders of his generation, he stood out for his leadership and ability in the air throughout his career.
Ayala captained the Argentina in a record 63 matches.
He played in three FIFA World Cups and made a total of 115 international appearances, behind only Javier Mascherano, Javier Zanetti and Lionel Messi in terms of international appearances.
He inherited the nickname El Ratón from the Argentine 1974 World Cup player Rubén Ayala, although they are not related.