There is a service tunnel hidden away at the Etihad Stadium. All away teams travel down it to enter, their coach passing underground, beneath the home supporters who greet Manchester City's arrival in transit.
About 100 yards away, towards Ashton New Road, Arsenal's two buses decided to turn themselves around. They then slowly reversed all the way in, a metaphor with tentacles when it comes to Wednesday night.
For their title challenge, for their occasional refusal to follow instructions on the height of Mikel Arteta's preferred defensive line.
Arsenal backpedalled from the off but more appropriately, were forced there by City, whose form continues to scale a different peak with each week that goes by, with each extension of this unbeaten run.