There are times when trying to make sense of Chelsea is a futile task. Lurching between extremes is their speciality. They were shambolic against struggling West Ham for 45 minutes, had Stamford Bridge ready to turn on Liam Rosenior at half-time and still found a way to mount a comeback so wild it left their opponents in a state of utter, uncontrollable rage at the end of an incomprehensible London derby.

Where to begin? With the end, perhaps, and Enzo Fernández running on to a cutback from João Pedro to make it 3-2 to Chelsea in the 92nd minute. It was some turnaround. João Pedro had made the difference after coming on at the start of the second half. The forward scored Chelsea’s first, heading home just before the hour, and was cool when he broke into the West Ham area when the game ran into added time. João Pedro had options. He could have shot and he could have crossed. Instead he threw West Ham by pulling the ball back to Fernández, who is beginning to resemble Frank Lampard with his knack of deciding games with late unnoticed runs from midfield.