Saints were forced to sign an emergency ‘keeper following injuries to both of their senior shot-stoppers Alex McCarthy and Fraser Forster in the past week.
Caballero, 40, has signed a contract until 5 January with the Saints. It’s expected he will feature in Southampton’s upcoming match against Arsenal on Saturday.
The Argentinian international successfully completed his medical at Staplewood today. He has been training at AFC Wimbledon since leaving Chelsea in the summer.