Southampton had previously been interested in Carlos Martín. However, according to 24sata.hr, the closure of the transfer windows for English clubs means they can no longer register him.

Southampton was mentioned among a group of clubs that were interested in Atlético Madrid's 24-year-old Spanish winger, Carlos Martín. It was reported that the competition for the player was strong, with Almería, Levante, Valladolid, Tenerife, and Castellón also having been linked with him. Martín has been capped four times for Spain's U21 team and has a contract with Atlético until 2029. His current valuation is €1.50m, according to Transfermarkt.