Martinez won the Europa League with Villa and reached the World Cup final with Argentina last season
Chelsea have agreed a £7.5m fee to sign Aston Villa goalkeeper Emiliano Martinez.
The Argentina international, 33, is set to undergo a medical in London and strengthen the goalkeeping group at Stamford Bridge.
It follows concerns over the performances of Robert Sanchez, particularly in the wake of Monday's 3-2 win over Fulham.
Sanchez, who has been Chelsea's first-choice goalkeeper since 2023, allowed Josh King's shot to slip through his grasp at the near post. He then spilled another effort into a dangerous area in the second half, allowing striker Gonzalo Garcia to score.
The move represents a remarkable turnaround in opinion at Stamford Bridge. Those in charge had been keen to back Sanchez but have opted to move for Martinez days before the transfer deadline.
Chelsea also have Mike Penders, a £17m signing from Genk, among their options. He is line to make his debut in the Carabao Cup against Luton Town on Thursday night.
Villa have been willing to sell Martinez since signing Japan goalkeeper Zion Suzuki from Parma for about £30m earlier this month.
It is also the latest in a series of deals between Chelsea and Villa.
The Blues signed forward Morgan Rogers from Villa for a club-record £117m, while Alejandro Garnacho moved in the opposite direction on an initial loan deal last month.
Striker Nicolas Jackson, valued at about £65m, was completing a medical at Villa Park on Thursday as he prepares to reunite with his former Villarreal manager, Unai Emery.
The clubs are known to have a close relationship. They were also involved in a deal widely described as a 'PSR swap', which saw defender Ian Maatsen join Villa and Omari Kellyman, now at Strasbourg, move to Chelsea.
Juventus attempted to sign Martinez earlier in the transfer window, but the deal collapsed because of concerns over a finger injury.
The Italian club instead signed Tottenham goalkeeper Guglielmo Vicario on loan.
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