Chelsea target Kepa Arrizabalaga has paid his release clause of £71m to La Liga, which allows him to leave Athletic Bilbao and clears the way for a transfer to the Premier League.
The deal would be a world record for a goalkeeper, surpassing the fee, believed to be up to £66.8m, that Liverpool paid for Alisson in July.
Spaniard Kepa, 23, is being brought in as a replacement for Thibaut Courtois.
Courtois has not reported for training and is being linked with Real Madrid.
The Belgium international, 26, was due at Chelsea's Cobham training ground on Monday, following his involvement at the World Cup.
Courtois has been a Blues player since 2011, when he signed from Belgian club Genk, and was loaned to Atletico Madrid from 2011 to 2014.
In Spain a player must buy himself out of his contract.
This is usually done by depositing the amount of the buyout clause with La Liga - Spain's equivalent of the Premier League - to release the player from his contract. The league then passes the money to the selling club.
Kepa is Spain's number two behind Manchester United's David de Gea and has one international cap.
He has spent the past two seasons in Bilbao's first team, making 53 La Liga appearances.
In January, he signed a new long-term contract with Bilbao until 2025, amid interest from Real Madrid.
Kepa is the second major signing to leave Bilbao this year, after Manchester City signed French defender Aymeric Laporte for £57m in January.