The Yorkshire club were among the teams attempting to persuade the centre-back to leave Spain, but Castrín has instead committed his future to Sevilla, ending the prospect of a transfer in the immediate future.
Valencia and Real Sociedad also made serious approaches, with all three clubs seeking to take advantage of the defender’s previous contract situation.
That agreement had been due to expire in June 2027, potentially giving interested clubs an opportunity to negotiate a transfer or wait until he became available as a free agent.
Castrín has now removed that uncertainty by signing an extension that keeps him at Sevilla until the summer of 2030.
His new deal reportedly includes a substantial salary increase, taking him onto first-team wages, as well as a €50 million release clause — approximately £43.5 million.
The new terms represent a significant change from his previous contractual position. Rather than allowing his deal to run down, Sevilla have secured the defender’s services for several more seasons and established a sizeable figure for any club hoping to prise him away.
For Leeds United, the outcome brings an end to an attempt to strengthen their defensive options with a player who has been progressing through one of Spain’s established football academies.
Castrín spent much of the 2024-25 campaign with Sevilla Atlético, the club’s reserve side, before receiving greater opportunities with the senior team.
His development has continued since then, and he has already made six appearances in LaLiga during the current campaign.
That progress helps explain why several clubs were prepared to pursue him despite his relatively limited experience at senior level. His performances have earned him increased involvement with Sevilla’s first team, giving the club a reason to secure his future before his previous contract moved closer to expiry.
The defender’s decision also means Leeds will have to look elsewhere if they wish to add another centre-back to their squad.
With Castrín now tied to Sevilla until 2030 and a €50 million release clause reportedly in place, any future move would require a considerably different financial calculation from the opportunity presented by his former contract.
For now, Sevilla have retained a young defender whose career is moving forward within their own system, while Leeds, Valencia and Real Sociedad have been left without the signing they pursued.