Bilbao: Spanish footballer Yeray Alvarez has undergone an operation to remove one of his testicles which had a cancerous tumour.

A medical report posted on Alvarez's football club Athletic Bilbao's website on Tuesday said: "An orchiectomy (removal of the affected testicle) has been performed and the surgery has passed without incident."

The 21-year-old will remain under observation for 24 hours, depending on his condition, reports Efe.

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It was revealed that Alvarez had testicular cancer on December 23 in a press conference in which the club's president Josu Urrutia and the team's medical chief Josean Lekue participated.