Football

River Plate face being relegated from Argentina's top flight, first time in their history. 33 titles(10 more than fierce rivals Boca Jnrs) and once known as 'The Millionaires', now face a two leg relegation play off with 2nd Div team Belgrano

wow, now watch for some serious grade A corruption to kick in to prevent this from happening.
Something similar once happened in Brazil with one of the big teams there in the early 90's. The team (i can't remember who) was relegated and then the brazilian F.A. chnaged the relegation rules so that the average points each team had over the last three seasons was the deciding factor not actual points. They stayed up!