There are games of football that feel like the inevitable product of their circumstances: system against system, the attacking and defensive patterns predetermined days in advance, the result telegraphed from the moment the first ball is kicked. Then there are the games in which Granit Xhaka runs the midfield, a mass brawl breaks out in the closing minutes and Eddie Nketiah scores twice against a team currently sanctioned by the UK government.
Chaos, farce, or high entertainment? Probably a mixture of all three. As shirtless Arsenal fans clambered over each other in the Shed End, as a fuming César Azpilicueta remonstrated with some of the few Chelsea supporters who were left in the ground, it was tempting to write this off as a classic slice of freak Premier League, a crunch London derby with all the logic and ambience of a Carabao Cup fourth-round tie.
