Italian soccer Fabio Cannavaro retired Saturday after doctors said his injured knee wouldn't allow him to keep playing.

The 38-year-old Italian center back, the captain of Italy's 2006 World Cup-winning team, said medical checkups in Italy and then in the United Arab Emirates this month revealed his knee wouldn't hold up for the second and last year of his contract with Dubai club Al Alhi.

''I'm very sad. Football is everything for me in my life,'' Cannavaro said. ''It's not a simple thing. Everyone says it has to come. But when it comes, it's a decision you have to face. I came back to Dubai to continue training. Unfortunately, the medical examiner didn't permit me to continue.''

Cannavaro is the only defender to be voted FIFA world player of the year, winning in the same year he led Italy to the World Cup title. He played in four World Cups in a 19-year professional career, and holds the Italian record with 136 international appearances.

Cannavaro signed with Al Ahli last year after Juventus wouldn't extend his contract. He also played for Real Madrid and Inter Milan.