Special Report has uncovered a worrying culture of football hooliganism in Ukraine - the co-hosts of Euro 2012.
We've spent six months investigating a group of Shakhtar Donetsk fans with neo-Nazi links and discovered that they'll be targeting England fans when the tournament kicks off next month.
Local officials hope that Euro 2012 will be a celebration of football but there remain serious doubts over their ability to safely deliver such a complicated event.
High up on the list of concerns is the threat of hooliganism; Ukrainian police admit that there are nearly 1,500 active football hooligans in the country.
Cass Pennant, a former football hooligan, told Special Report: "It's dangerous for English fans to go anywhere outside of England; the reputation goes before England fans worldwide when it comes to the word hooliganism.
"That was established in the 70s and the 80s. Through that reputation, the England fan has that as a burden today because it is a different fan-base.
"What you've got in effect is the hunter has become the hunted. The Polish and the Ukraine guys - it's their way of life; they live it. They are on it all week. It's a big build-up and they want to test themselves.
"If they test themselves against the English, the kudos is massive to them. Suddenly people will look up because they fought England and say 'what about these Ukraine guys?'"
Our investigative team managed to infiltrate a hard-core gang of ultras, called 'The Donetsk Company' at their operational HQ, in their combat gym and during a brutal, organised fight with a company of ultras from Dynamo Kiev.
The Ukrainian police have told us that Tolik, the leader of the Donetsk Company, is at the top of their hooligans' watch list, but he remains free to attend matches, including those at this summer's European Championship.
If you missed our Special Report it's repeated on Sky Sports 1 HD at 10pm on Tuesday. You'll also be able to catch it on Sky Anytime later this week.