The 26-year-old from Bugojno has made a name for himself as a bruising challenger who has added bulk to Croatia's back line.
Strong in possession and a potential aerial threat Tomas made his international debut against Poland in 1998.
He has since passed in and out of the team following spells at Dinamo Zagreb and Serie A side Vicenza.
He also shares his name with a former Bosnian king who ruled from 1441-1461.