The frustrated fans took this extraordinary action to voice their strong disapproval of the way 'their' club was being run by the controversial owners from the United States, the Glazer family.
The owners have seen the club accrue debts of an equivalent of $767 million since taking over in 2005.
They are real, genuine fans, the English.
Football worldwide needs more of these proper supporters who love their club and less of the spectator types who are prepared to be trod on and treated like customers by unscrupulous owners and do nothing about it.
The United supporters' anger has boiled over in the two weeks since the famous club was part of the failed Super League breakaway.
Supporters demonstrated near the team hotel in Manchester and later gained access to the Old Trafford pitch before the two teams even travelled to the ground.
A flare set off by fans was launched into the stands where the Sky Sports television team was already broadcasting more than two hours ahead of the scheduled kickoff.
The protest later turned ugly and violent when police were called in to disperse the crowd.
It is two weeks since the Super League plan by Europe's elite clubs - dubbed the 'dirty dozen' - was crushed after mass fan disapproval mainly from England.
And now a big match in a big league that would have been shown live around the world was called off.
So instead of watching the likes of Edinson Cavani and Mohamed Salah weave their special brand of football magic, we saw a vigorous protest that showed in no uncertain terms the level of anger among the game's main stakeholders: the fans.
There is no doubt that events of the last couple of weeks have shown that the game has reached a stage where fans feel that enough is enough and their blatant exploitation has to end.
All those filthy rich owners who think they can do whatever they like to boost their investments must be made to realise that 'people power' is not just a cliche but a tool with which all those who care and love their club through generations can have a say in how it is run.
The Manchester United fans' protest that will have serious ramifications should serve as encouragement to other supporters from other clubs in England and beyond.
The blunt message should be: 'don't mess with us any more'.
The action showed what can be achieved if supporters unite in a common cause to protect their club from the whims of owners whose only interest is the bottom line and to hell with history and tradition.
If fans are unhappy about any aspect of the game they love - like the silly scheduling or the detested VAR, for example - they should voice their disapproval in strong terms ... like boycotting matches.
A drastic measure, for sure, but maybe it's the only way the suits will ever listen to us plebs.
