A Carabineri federal policeman suffered a hand injury as clashes broke out ahead of the Serie A match between Atalanta and AC Milan in Bergamo on Sunday.
Violence broke out as police tried to form a barricade to keep rival supporters apart as a coach-load of Milan fans arrived at the stadium, Italian news agency Ansa reported.
Those fans came into contact with police and tensions rose, resulting in the throwing of bottles and smoke bombs.
Calm had, however, been restored ahead of the 3pm kick-off.
Follow Emirates 24|7 on Google News.