Footage has surfaced of fans fighting each other in the stands during Manchester United's win over Arsenal in a pre-season friendly.
United triumphed over their Premier League rivals in a 2-0 win, with goals from Bruno Fernandes and Jadon Sancho.
A penalty shootout followed the result, which the Red Devils also won 5-3 to give Arsenal boss Mikel Arteta something to ponder.
The game was played in front of a sold-out crowd at the MetLife Stadium in New Jersey, which has a capacity of 82,500.
But as tempers flared on the pitch between Lisandro Martinez and Martin Odegaard, there was further violence in the stands.
Shocking footage has caught fans, who appear to be wearing Arsenal shirts, throwing huge punches and even one fan trying to take another's shoe off.
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It left some bloodied and others on the steps of the stadium while others intervened and threw further punches.
After the rage subsided, staff escorted those responsible away from their seats and presumably out of the ground.
This all went on as the match continued with live action of the game being played on a screen in the video.
It is not known what caused the fight, though it did seem to take part in a section of Arsenal fans.
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As for the on-pitch action, the Gunners had a troubled time against United as they went two goals down in 45 minutes.
Fernandes opened the scoring with a long-range effort, though Aaron Ramsdale might have felt he could have done better.
And an error from Gabriel Magalhaes allowed Sancho to race through on goal to double the lead.
Arsenal could find no reply in what was the first time Arteta played a midfield three of Kai Havertz, Martin Odegaard and Declan Rice.
Despite not clicking immediately, Arteta has high hopes after spending close to £170million on Havertz and Rice.
The Spaniard told Arsenal's club website: “When they play 55 times together they will be better.
"It will flow better, they will understand each other better and will be more dominant and better.
“But it takes time to glide and we have to respect that.
"But I saw a lot of positive things, and things I like much more than the game we won the other day against the MLS even though the result is very different.”
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