According to Spanish media, Castellón was one of several clubs interested in Atlético Madrid's 24-year-old Spanish winger, Carlos Martín, alongside Almería, Levante, Valladolid, Tenerife, and English club Southampton. A loan move for Martín to Almería was not completed at the last minute after the clubs had reached an agreement. The Spanish list AS reported that the deal was not completed on time because the required documentation was not finalized before the market closed, preventing the transfer from being registered with La Liga. Martín, who has 4 caps and 1 goal for Spain U21, joined Atlético in July 2023 and his contract runs until 2029. His current market value is estimated by Transfermarkt to be €1.50m.