The 24-year-old versatile Belgium international stopper, who can operate in the centre or on the right side of defence, is a wanted man with a host of top European sides after him.
Both Spurs and, most recently, Norwich from the Premier League have expressed an interest.
Despite the strong Premier League links, it is being reported that German Bundesliga outfit Bayer Leverkusen are leading the race to secure his signature should he decide to leave Amsterdam.
The Reds have been after new central defenders since the close of last season following the departure of Jamie Carragher and the uncertainty over the future of Martin Skrtel.
They are also after full-backs and have been on the trail of both Lille starlet Lucas Digne and Valencia full-back Aly Cissokho.