United boss Jose Mourinho had milk and water thrown on him in the wake of City's crushing 2-1 at Old Trafford.

Express Sport understands Mourinho took exception to the manner in which Pep Guardiola's men were celebrating their win before sparks flew.

The incident would all have been caught on camera had United made a different decision in the week before the game.

City requested to film in the away dressing room on Sunday as they wanted to use the Old Trafford footage for a documentary.

That follows the signing a £10million deal for a behind-the-scenes film to be shown on Amazon Prime next autumn.

However, United rejected the City request meaning their cameras weren't allowed in. Subsequently, the flashpoint wasn't caught on cameras and will never be seen by fans.

Manchester United felt the tunnel area would be too cramped given there were 23 television rights holders for the game already.

They were prioritised rather than trying to accommodate cameras from a company that is not one of the Premier League's £10billion broadcast partners.

Mourinho walked to the City dressing room to ask their players to show more respect as music blared from the visiting changing room.

But a war of words ended up breaking out - with Mourinho and Ederson believed to have been yelling at each other in Portuguese as a melee took place.

Mourinho walked away but went on to accuse City of being 'protected by luck' after claiming his team were denied a 'clear penalty' against their bitter rivals for the second successive season at Old Trafford.

Ander Herrera was booked for diving by referee Michael Oliver after a challenge by Nicolas Otamendi with 10 minutes remaining.

Mourinho was convinced it was a spot kick and claimed afterwards that City were benefiting from divine intervention.

He said: "Manchester City are a very good team and they are protected by the luck, and the gods of football are behind them.

"My first reaction is I feel sorry for referee Michael Oliver because he had a very good match but unfortunately he made an important mistake.

"It is like last season, exactly the same. You can speak about anything you want, you can bring any football theory, you can bring the stats, the ball possession, you can bring everything you want but, like last season, it is a huge penalty in a crucial moment of the game."