Minnesota sports fans spend a fair amount of their fall weekends rooting hard for four teams: The Vikings, the Gophers football team ... and whatever teams are playing against the Packers and the Badgers football team.
If it happens to be a weekend when the Vikings are playing the Packers or the Gophers are playing the Badgers — or that ultra-rare weekend when both rivalry games are happening — we might as well shut down the state (or at least the Minnesota/Wisconsin border).
In the hierarchy of sports rivalries, those two are (at least in my mind) 1A and 1B in Minnesota.