The Reds were heavily linked with the Greece international during the summer of 2013, but failed to get a deal over the line for his signature.
Since then their interest seemed to have cooled, but reports now claim that the Merseysiders are firmly back in the race for the Schalke man.
Papadopoulos is currently on loan at Bayer Leverkusen, but he’s expected to return to Gelsenkirchen at the end of the season to be sold on.
And with his contract running down, Schalke are unlikely to demand any more than £5m for their man.
Papadopoulos is a commanding centre-back who has been praised for his aggressive playing style and fearless nature.
Arsenal and Spurs have also been linked with the 23-year-old, who has suffered with knee problems in recent years.