Whats the biggest rivalry in all of sports

I think that all professional sports teams have certain rivals in their leagues. In hockey, all of the teams in the NHL seem to have at least one huge rival team. For the Buffalo Sabres, I would have to say that the Toronto Maple Leafs are the biggest rival, and most Sabres fans would agree, I'm sure. These teams have been rivals for as long as I have been a Sabres fan (1970's), and the games between these teams are always exciting. Part of the continued rivalry is due to past games and experiences between these teams and the media hype, but a lot of it is because Toronto and Buffalo are so close geographically. It is very easy for fans to cross the border to attend games in the opposing city; it's only about 90 minutes away. So the arenas for these games always have a huge number of fans for the opposing team, in addition to the die-hard home-team fans. This makes for an exciting game for the players as well as for the fans.

i think in italian football the biggest rivalry is inter-milan