Slovenia will take on Algeria and the United States before facing England on 23 June. Few fancy Slovenia to make much noise in the group, but ex-West Bromwich Albion midfielder Koren now a free agent - believes they can challenge for a place in the knock-out stages.
"We're not afraid of England, we're not afraid of anyone," the Slovenia captain said in The Sun. "People say England will have an easy game against us but you just wait and see.
"Our display last year at Wembley, when we lost 2-1, showed what we are all about. We're not scared, no way."