The Croatia–Serbia football rivalry is a competitive sports rivalry that exists between the national football teams of the two countries and their respective sets of fans. The rivalry has been considered to be one of the most hostile in world football, despite the two national teams not having met often. Tensions between the nations are fueled by political differences which arose during the 20th century based on the events of World War II and the breakup of Yugoslavia. The two rivals had previously represented the Yugoslavia national football team, and contributed the bulk of the teams footballers during almost 70 years of its existence.