Bidasoa secured its first Copa del Rey in January 1991 in Alzira, after eliminating Teucro in the preliminary round. The team, coached by Juantxo Villarreal, traveled to Valencia for the final phase, where they narrowly won the Gipuzkoan derby against Xerox Arrate, led by a young coach Jordi Ribera, with a score of 23-20.

In the semifinals, against the powerful Teka, Bidasoa delivered a major surprise. Despite trailing 10-9 at halftime, they achieved a convincing 19-27 victory, showcasing their resilience and effectiveness. This triumph paved the way for Bidasoa to claim its first Copa del Rey, with key contributions from goalkeeper Miguel Ángel Zúñiga and players like Alfreð Gíslason (9 goals) and Bogdan Wenta (8 goals).

Zúñiga recalls that the team felt immense pressure, having lost three previous finals. “We can’t lose anymore. We have to win it, just reaching isn't enough,” was the prevailing message in the locker room. The team's unity and determination were crucial, as there was no need for coach Juantxo or president Beñardo García to speak; it was a collective feeling among the players.

That Elgorriaga Bidasoa team was very complete, boasting a strong defense and a devastating attack. It featured players like Xabier Mikel Errekondo and prolific scorers such as Bogdan Wenta and Alfreð Gíslason. Zúñiga emphasizes that “we were a wall,” referring to their defensive solidity. In the final, against Atlético de Madrid, Bidasoa faced a different opponent than FC Barcelona for the first time in their Copa finals, marking a turning point in the club's history.