Yeray Alvarez has signed a new deal with Athletic Bilbao until 2022, just six weeks on from undergoing cancer surgery.
Having been diagnosed with testicular cancer, the 22-year-old underwent surgery in December.
But the defender has already resumed his playing career, returning to the side in last weekend's 3-0 defeat to Barcelona.
Yeray has made 18 appearances in all competitions this season after breaking into the first-team picture under Ernesto Valverde.
He told a news conference: "For me it is something great to renew for this club, which is where I have begun my career. I am very happy.
"This end of the year has been very fast, everything that has happened to me. From the illness to the renewal.
"I'm really comfortable with my team mates. We are all friends, mates and we all enjoy playing together.
"The support given from all the people in these months - it is really valuable."
His new five-and-a-half-year deal includes a buy-out clause of €30million.