MADRID, July 29 (Xinhua) -- Sevilla has completed its fifth signing ahead of the new La Liga season with the arrival of Spain under-20 international left-back Julio Diaz from Atletico Madrid.

Spain's defender #3 Julio Diaz and Brazil's forward #19 Luighi fight for the ball during the 2025 FIFA U-20 World Cup football match between Spain and Brazil, at the National Stadium in Santiago on October 4, 2025. (File photo: AFP)

Diaz follows Arouna Sangante, Juan Iglesias, Jon Guridi and Odysseas Vlachodimos, whose loan move has been made permanent, after the southern Spanish club paid Atletico one million euros for 50 percent of the player's rights.

The defender has signed a four-year contract through June 2030, although Atletico has retained a buy-back option.

Diaz spent the past two seasons with Atletico's B team, while also making four first-team appearances under Diego Simeone.

His arrival at Sevilla will raise further doubts over the future of Joaquin Martinez Gauna, better known as Oso. The 23-year-old impressed at left-back as Sevilla pulled away from the relegation zone in the closing weeks of the 2025-26 season, but has yet to agree a new contract.

Sevilla could now decide to sell Oso this summer rather than risk losing him on a free transfer in 12 months.