Liverpool have been given FIFA permission to sign Argentina's Javier Mascherano from West Ham.
The midfielder's move to Anfield was initially in doubt because he had already played competitively for two clubs this season.
Mascherano failed to make an impact after joining West Ham last summer along with fellow Argentine Carlos Teves.
Fifa said: "The Fifa single judge ruled that Javier Mascherano is eligible to play in official matches with Liverpool with immediate effect."
A Liverpool spokesman confirmed: "Ffa has confirmed the player is entitled to play for Liverpool.
"However, the move from West Ham still needs to be ratified by the Premier League - and we await their decision."