Every great team needs a rival: an opposing force that pushes each side to the very limit of their capabilities. This is true of any sport but with football, all of the greatest sides, both domestically and abroad, have achieved greatness in part due to having a competitor who was constantly nipping at their heels.
In 1990s English football, Man Utd were pushed by first Blackburn and then Arsenal, with the latter forming one of the all-time great rivalries with United towards the end of the decade and into the next.
The great Barcelona side under Pep Guardiola were pushed to breaking point by Jose Mourinho’s Real Madrid at the beginning of the 2010s, with El Clasico games almost turning into something resembling a civil war than a game of football.
