The 29-year-old has been without a club since leaving the Serie A side in the summer and is now set to bolster Saints’ troubled backline.
Virgil van Dijk’s injury compounded the January exit of captain Jose Fonte to West Ham, with Claude Puel’s side subsequently conceding 11 goals in their next four matches in all competitions.
Southampton need a February pick-me-up if they are to get their ailing season back on track.
Southampton are set to sign Martin Caceres
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Southampton have missed Virgil van Dijk
And Caceres is now set to add much-needed experience to Puel's defence.
The 29-year-old spent five years at Juventus, winning the Serie A title every season.
However, the deal is still a few days from completion as a work permit and clearance is finalised.
Martin Caceres won five league titles at Juventus
The Uruguay international has reportedly turned down interest from AC Milan, Sunderland and Crystal Palace, favouring a switch to the side who take on Manchester United in the EFL Cup final on February 26.
Saints boss Claude Puel needs reinforcements with his side aiming to win a first trophy since winning the Championship in 2012.
Caceres is unlikely to be able to slot straight in the team given he has not played since last February after having surgery on a torn right Achilles tendon, but could be named as a substitute.