Athletic Bilbao defender Yeray Alvarez has been diagnosed with testicular cancer, the club have confirmed.
The 21-year-old, who made his LaLiga debut last year, is due to undergo surgery next Tuesday.
Athletic president Josu Urrutia and club medical chief Jotxean Lekue held a news conference on Friday, at the behest of the player, in which they confirmed the diagnosis and expressed their admiration for the player's positive approach.
"During the day [on Thursday] Yeray had medical tests which detected a tumour in one of his testicles," Lekue said.
"It requires an operation which will take place next week.
"The player is okay, strong, calm. He's showing maturity, not only on the pitch, but also off it. He's optimistic. We're all with him, too."
Messages of support have been sent to Athletic and Yeray since the announcement, including from LaLiga rivals Villarreal and Osasuna and team-mate Mikel San Jose.
"You have all of us by your side!" he tweeted.