The Greek international is famed for his juxtaposing baby face and short temper but has always been rated as a defender of real pedigree, having made his Bundesliga debut as an 18-year-old.
However, injury problems have seriously hampered the 24-year-old’s development, managing just 91 appearances throughout six years in the German top flight with Bayer and former employers FC Schalke.
That includes just 16 Bundesliga outings last season, in which he averaged 1.8 tackles, 1.8 interceptions, 3.8 clearances and four successful aerial duels per match.
And according to Mirror Football – who The Stoke Sentinel quote directly – Stoke City are now lining up a £12million transfer bid for the 6 foot centre-half, who can also operate in defensive midfield.
Manager Mark Hughes is keen to provide competition for the likes of Ryan Shawcross, Marc Muniesa and Philipp Wollscheid.