Liverpool have confirmed the signing of defender Steven Caulker on loan from QPR until the end of the season.
The club have announced the relevant paperwork has been completed in time to allow the centre-back to be eligible for selection for the visit of Arsenal in the Premier League on Wednesday night.
Caulker has been on loan at Southampton but has found first-team opportunities limited, making just eight appearances for the Saints, including just one in the league.
The 24-year-old is expected to train with his new team-mates on Tuesday afternoon after travelling to Merseyside from London.
Liverpool boss Jurgen Klopp was desperate for defensive reinforcements after injuries to central defensive quintet Martin Skrtel, Dejan Lovren, Mamadou Sakho, Kolo Touré and Joe Gomez.
Southampton boss Ronald Koeman said: "Steven came in in the summer before we signed Virgil van Dijk because we had long-term injuries and he was a back-up.
"He didn't play a lot and normally we have more defenders for that position. I am not to stop his opportunity to play for Liverpool."
Tiago Ilori was handed his Liverpool debut by Klopp in Friday's 2-2 FA Cup draw at Exeter City after being recalled from his season-long loan at Aston Villa.
Klopp confirmed in his pre-match press conference that Toure is in line to return against his former side on Wednesday, with Sakho and Lovren struggling to be fit for the game.
Tottenham academy graduate Caulker, who was capped by England in a 2012 friendly against Sweden, is expected to be named on the bench for the clash with Arsenal.