Athletic Bilbao defender Yeray will have surgery to remove a tumour from his right testicle next week.
The 21-year-old Basque, who has made 10 league appearances for Bilbao this season, asked president Josu Urrutia and club doctor Joxean Lekue to reveal his diagnosis at a press conference convened on Friday evening.
Quoted on Athletic's official Twitter account, Urrutia said: "Yeray has a tumour in one testicle and will be operated upon next week.
Enfermedad de Yeray Álvarez https://t.co/5qnuB6MtA7 #athletic
- Athletic Club (@AthleticClub) December 23, 2016
"He has decided that he wanted us two to convey the news while he spends time with his family. I have seen him and he is calm and relaxed.
"I have told him that he is not alone and that we will get through this together.
"He was experiencing discomfort and so we did an ultrasound. That rang alarm bells and we carried out further tests today.
"We confirmed that there was a tumour in his right testicle and the best course of action is to remove that tumour.''
Urrutia expects the surgery to be performed on Tuesday, Dec. 27.