The 40-year-old, who has been a free agent since leaving Stamford Bridge at the end of last season, will join the south-coast club until January 5.

Saints boss Ralph Hasenhuttl is currently without both Alex McCarthy and Fraser Forster due to injury and criticised the former on Saturday after he failed to reveal the extent of his hamstring issue during the 1-1 Premier League draw against Brighton and Hove Albion, in which McCarthy conceded an equaliser deep into stoppage time.

"This is something we cannot accept," Hasenhuttl said after the game. "There must be a message: 'I cannot jump,' and then we can make a change.

"We still had one change [available] at the end, and I could have changed the goalkeeper if necessary in this moment.

"But Alex must be definitely more professional than that. This is what I missed from him today in such a game."

Caballero is set to be part of the squad for Southampton's trip to Arsenal on Saturday.

The Argentine, who won five caps for his country, made 48 appearances for City, where he won the Carabao Cup. He then went on to play 38 times for Chelsea, winning the FA Cup, Europa League and Champions League.

He previously played for Elche and Malaga in Spain, and Boca Juniors and Arsenal de Sarandi in his homeland, winning the 2003 Copa Libertadores with Boca.