United take on AC Milan on Wednesday at Old Trafford with a 3-2 first-leg advantage, while Chelsea trail Inter Milan 2-1 ahead of the return fixture at Stamford Bridge on 16 March.
Holland too has suffered at the hands of soccer yobs and in Italy mounting trouble came to a head in 1995 when a 24-year-old Genoa fan was stabbed to death by an AC Milan supporter.