and have been warned they will be the subject of an investigation after an in Sunday's clash at the Emirates Stadium. Tensions boiled over during the heated third-round grudge match despite playing over 70 minutes with 10 men.

Referee Andy Madley wasn't shy in dishing out yellow cards as he teetered along the margins of losing control in the capital, booking nine individuals, including Mikel Arteta.

Diogo Dalot received two cautions, resulting in his dismissal on the hour mark, which only spiced up the conflict that had already been brewing.

The beacons lit after Madley adjudged Harry Maguire to have fouled Kai Havertz inside the box, leaving United's players furious.

It handed Arsenal the opportunity to turn a 1-0 deficit into a lead after Gabriel Magalhaes cancelled out Bruno Fernandes' opener.

Cameras cut from a replay of the soft incident to a mammoth bust-up, which saw Alejandro Garnacho grappling with Havertz.

Manuel Ugarte then got involved and appeared to push his head into the German forward's, sending him tumbling to the ground.

The players involved escaped punishment, with Madley missing the incident and no VAR in operation in the FA Cup third round.

However, former PGMOL chief and FIFA official Keith Hackett believes there is punishment coming both clubs' way for failing to control their players.

And Hackett recalled a similar incident during his career which ended in sanctions as severe as points deductions following an FA review.

"The mass confrontation which may have also seen a player headbutting an opponent will be the subject of an investigation by the Football Association," he told .

"Years ago, I was in the middle of a mass confrontation involving what was a 21-man brawl.

"I decided not to red card anyone on the basis I might have had more than a handful walking in the direction of the tunnel.

"So I submitted a detailed report to the Football Association, who investigated and both teams were deducted points. I have no doubt that both teams will be charged for failing to control their players.

"The question that we can ask - if VAR was in operation, that would have been reviewed and the result may well have secured a different outcome."

Losing Ugarte would be disastrous for Ruben Amorim, who has discovered his strongest midfield duo in the Uruguayan and Kobbie Mainoo.

It could put a damaging dampener on his best day as United boss yet.