Sorcha, one thing all the guy/girls will tell you is that, from your examples, you really "ain't seen nothing yet". Rangers/Celtic rivalry beats any inter-team rivalry anywhere in the world. Bill Shankly famously said that football isn't a matter of life and death, it's far more important than that. The Old Firm have taken even that to extremes. Fatalities linked to this rivalry are thankfully a lot less common these days, but are still far from unheard of. US Football and World Cup games are simply no comparison to make.