Liverpool have been put on high alert after it emerged that their defensive target Joel Matip has turned down a new contract, according to the Daily Star.
The Premier League side; who currently sit ninth in the standings, 12 points adrift of Manchester City in fourth spot, were linked with a move for the Schalke centre-half during the previous January transfer window.
The 24-year-old, who has 27 international caps for Cameroon, has scored four goals in 25 appearances in all competitions for the Bundesliga outfit so far this season.
Matip, who was scouted by Schalke back in July 2000 as an eight-year-old, could leave the Veltins Arena this summer as his current deal with the German side expires at the end of the 2015-16 campaign.
The Cameroonian broke into Schalke’s first-team squad during the 2009-10 season, making his debut against FC Saarbrucken, where he has since gone on to score 23 goals in 242 games for the club.