Not for the first time, there is panic in the Manchester United defence. Bukayo Saka is walking towards the corner and Nicolas Jover is positioned on the touchline. Rasmus Hojlund is clinging onto William Saliba as if he is reaching for a log while tumbling down a rapidly moving river. The Emirates senses the opportunity and understands what is happening: there is a queue of towering Arsenal players stationed at the back post and the United defenders are wearing expressions of grave concern. Suddenly, in a box of moving shadows, danger lay around every corner, every decoy a potential target.
Seconds later, Ruben Amorim was in the dugout rubbing his face, as what should have been a cohesive, organised block unravelled into strands. “The set pieces changed the game,” Amorim admitted. On a night where Arsenal initially didn’t look like scoring from open play, Mikel Arteta’s side won due to two goals from corners to move within seven points of Liverpool. In all of this, United became the latest victims of Arsenal's not-so-secret weapon. Since the start of last season, no team in Europe has scored more goals from corners than their 22. “Set-piece again, ole, ole, ole,” was the song ringing around the Emirates.