LONDON • Manchester United found out just how loud their noisy neighbours could be after Manchester City's 2-1 Premier League win at Old Trafford on Sunday.
United manager Jose Mourinho, unhappy with the way that City players were celebrating as he passed by the away dressing room, reportedly told the victorious side to keep their music down.
That led to a bust-up in which City players threw milk and water at him while bottles and punches were thrown.
Police officers and stewards had to separate up to 20 players and members of staff from both clubs, and the Football Association (FA) is demanding answers from United and City.
City assistant manager Mikel Arteta was left with blood streaming down his face. His eyebrow was split open during a melee in a narrow corridor outside City's dressing room and there were unconfirmed reports that another member of Pep Guardiola's backroom staff needed medical treatment.
Mourinho is understood to have approached the City players in an attempt to ask for more respect to be shown to the losing team, only to be stopped by Ederson.
The City goalkeeper, who was standing just inside the dressing room door, allegedly grabbed Mourinho's arm to block his path.
The two started shouting insults at one another in Portuguese.
Mourinho is said to have accused the Brazilian of play-acting to waste time and then reverted to English, screaming: "You f**king show respect. Who are you?"
At least one member of the City dressing room then squirted water and threw cartons of milk towards the opposition manager, eyewitnesses said.
Mourinho then stormed off to do his television interviews.
Other players then became involved and United striker Romelu Lukaku was said to have been prominent as the confrontation escalated into something much more serious, described by one person as being reminiscent of a pub fight.
Referee Michael Oliver did not witness what happened, so the FA has not received a report on the matter from him but it has given the clubs until tomorrow to reply to a request for observations.
Early accounts indicated it was a much more serious incident than the infamous "Battle of the Buffet" in 2004, when Arsenal were the opponents and then-United manager Alex Ferguson was hit by flying pizza slices after his side ended the visitors' 49-match unbeaten run.
This time, City ended United's 40-game unbeaten home streak, while extending their winning run in the Premier League to 14 games - the most by a team in a single English top-flight season.
THE GUARDIAN, THE TIMES, LONDON, AGENCE FRANCE-PRESSE