Unai Simon has signed a new five-year contract with Athletic Bilbao that does not include a release clause.
Goalkeeper Simon, 23, has reportedly been monitored by Real Madrid and Inter and would have been available for €50million under the terms of his previous deal.
However, after seeing Chelsea trigger an €80m buy-out fee in Kepa Arrizabalaga's contract at San Mames in 2018, Athletic have moved to avoid a repeat.
Simon moved into the first team following Kepa's exit and Thursday's announcement coincided with the second anniversary of his LaLiga debut and a first call-up to the Spain squad from Luis Enrique.
"I've been here since I was 14 years old. Being here until 2025 is a dream for me. I am very proud and happy for the trust the club has placed in me," he said in a club interview.
"It's been a complete, very beautiful day for me."
Sporting director Rafael Alkorta added: "Both parties were clear about what we wanted and it was easy for us to reach an agreement.
"Unai Simon's commitment to Athletic is outstanding. It is a day for us all to be happy. Unai is growing a lot and he wants to continue doing so. We have a top goalkeeper in Europe for many years to come."
