Portsmouth missed the deadline to exercise their option for a permanent purchase of Gustavo Caballero from Santos. Portsmouth held an exclusive transfer option that was believed to be valued at approximately £2.5m. The club is aiming to renegotiate his £2.5million transfer fee with the Brazilian club. Gustavo Caballero's agent, Enzo Prono, confirmed that Portsmouth are trying to renegotiate a possible deal. Prono stated that they are waiting for the outcome.

Portsmouth manager John Mousinho has confirmed he wants to sign Gustavo Caballero permanently, but only if the terms of a deal can be renegotiated with Santos. Mousinho said the main issue will be the price and whether Portsmouth considers it a fair reflection of their market valuation. He stated that concerning the player, they will wait until the summer and attempt to negotiate. Mousinho also explained that the fixed transfer fee in the option is not the only price the club could possibly pay, as they could make an offer at any time. He clarified that the only offer they would make is what they value the player at, and added that he does not yet know that value because the conversation has not occurred.

Portsmouth secured Gustavo Caballero from Santos on deadline day of the winter window, with the deal structured to give the Championship club an option for a permanent transfer. Portsmouth have taken the 24-year-old Paraguayan winger on loan until June 2026. The agreement already generates income for Santos, with the Brazilian club set to receive around £850,000 (€1m) from the operation. Portsmouth can buy Caballero’s rights if he reaches a defined target during his time in England; that target is tied directly to appearances in the Championship, a condition described in Brazil as realistic and likely to be met. If the clause is triggered, Portsmouth would pay around £4.25m (€5m) to secure 80% of the player’s economic rights. The remaining 20% would stay with Nacional, Caballero’s former club, which retains a sell-on percentage for any future transfer. Caballero only joined Santos in July 2025, arriving on a free transfer after leaving Nacional. He quickly was no longer part of the plans of head coach Juan Pablo Vojvoda. Portsmouth’s proposal arrived last week and negotiations proceeded quickly. Caballero, whose contract with Santos expires in December 2028, has a current market value of €1.00m. This season, he has made one appearance in Série A and one in the Campeonato Paulista.