Five of the best rivalries
Rangers v Celtic: The animosity between these Glasgow rivals is rooted in sectarianism. An on-pitch battle at Hampden Park after the 1980 Scottish Cup final led to the banning of alcohol in stadiums. Celtic manager Neil Lennon has received death threats and bullets through the post.
Lazio v Roma
Rivalry dates from Lazio resenting Roma's formation, by dictator Benito Mussolini, as a 'superclub to represent Rome'. In 1979 a Lazio fan was killed by a flare fired from the Roma end and a game was abandoned amid violence five years later.
Real Madrid v Barcelona
El Clasico was once coined 'a re-enactment of the Spanish Civil War' due to Real's association with General Franco and Barca's strong Catalan identity. Luis Figo had a pig's head thrown at him after he switched from Barca to Real.
Fenerbahce v Galatasaray
Istanbul's fiercest derby began in 1934 when riots took place on and off the pitch during a friendly. Graeme Souness infamously inflamed tensions after Galatasaray's 1996 Turkish Cup win, planting the club's flag in the middle of Fenerbahce's pitch.
Boca Juniors v River Plate
A rivalry based on social class and money, with 'the Millionaires' River Plate moving from the docklands area of Buenos Aires to a more affluent district in 1925. This season marks the first since Boca's formation in 1905 that a league derby will not be played due to River Plate's relegation.