Hansi Flick's anger in the 86th minute was no ordinary touchline outburst. It was fury dictated by a new law, a strict rule and a punishment that nearly turned the top-of-the-table clash on its head at the Wanda Metropolitano.
Barcelona led Atletico Madrid 2-1 and were trying to hold on to the three points. One substitution nearly left them playing with ten men for a full minute, and Flick, for all his customary calm, could not stay silent.
A match on the brink of exploding
Barcelona against Atletico Madrid sat on a knife-edge. The encounter at the Riyadh Air Metropolitano could have shaken up the standings had Atletico claimed the three points.
Things started to drift that way. Giuliano struck early and the Rojiblancos looked the better side. But Barcelona steadied themselves and turned the result around, though the narrow 2-1 scoreline kept the tension alive until the final whistle.
The moment of anger in the 86th minute
Flick himself embodied that tension. In the 86th minute the German coach brought on Karim Adeyemi in place of Anthony Gordon, who felt compelled to have a word about the switch.
The Englishman took longer than his coach expected and trudged off the pitch unhappy with his walk towards the goal line. Gordon, looking surprised, quickened his steps and shook hands with Adeyemi.
Flick urged the Englishman to hurry, so he left the pitch in a state of disbelief.
The 10-second rule
Flick's frustration makes complete sense. From this season, delaying a substitution carries a penalty.
To stop time-wasting, the player coming off must leave the pitch within 10 seconds of the substitution board appearing. If he doesn't, the substituting team drops to ten men, and the replacement has to wait a full minute before entering.
Had Gordon dawdled any longer, the Blaugrana would have played with ten men for a minute while Atletico hunted an equaliser.
The precedent of Real Madrid and Inter
The law was applied for the first time in early September during a Champions League match between Real Madrid and Inter Milan, according to "Mundo Deportivo".
Vinicius took longer than necessary in the 87th minute, and Carreras, his replacement, could only enter the match after 60 seconds had passed. Real Madrid, and Mourinho in particular, protested strongly at the time, but the officials applied the law correctly.
So Flick knew 10 seconds can be the difference between top spot and catastrophe. That is why his anger at Gordon was no mere attack of nerves. It was a warning that the new football shows no mercy to anyone a single second late.