Tigers snap up Caceres
The Tigers have taken over the 20-year-old's registration, with chairman Adam Pearson confirming Caceres is neither on loan nor on trial.
He said: "He's not on loan or trial, we have taken over his registration from Southampton."
Caceres impressed Hull's caretaker boss Billy Russell when scoring twice for the club's reserve side in a 6-1 thrashing of Mansfield last week and he will continue his march towards match fitness by playing for the second string against Carlisle in midweek.
The Argentinian-born Australian failed to make the grade on the South Coast after arriving from Perth Glory in September 2000 and never appeared in the Saints first team.
Earlier this season he spent a month on loan with Second Division Brentford and will be hoping his switch to Boothferry Park will kick-start his professional career.