(This list is incomplete; you can help by expanding it.) A sports rivalry is intense competition between athletic teams or athletes. This pressure of competition is felt by players, coaches, and management, but is perhaps felt strongest by the fans. The intensity of the rivalry varies from a friendly competition on one end to serious violence on the other that, in one case (the Football War), was suggested to have led to military conflicts. Owners typically encourage rivalries as they tend to improve game attendance and television ratings for rivalry matches, but a rivalry that gets out of control can lead to fighting, hooliganism, rioting and some, with career-ending or even fatal consequences.