Roy Keane allegedly HEADBUTTED by a fan at the Emirates

Roy Keane was allegedly HEADBUTTED by a fan inside the Emirates Stadium during Arsenal's victory over Manchester United.

As the 52-year-old made his way to do his post-match media duties for Sky Sports, he was confronted by a fan at the top of the west stand as he was waiting for a lift to take him pitchside.

According to The Daily Mail, the man aimed a headbutt at the former Man United captain and hit on the chest and chin, but was 'prevented from inflicting serious physical damage'.

A video emerged online of Micah Richards restraining a man, but the supporter had left the area before security guards arrived at the scene.

The incident between Keane and the crazed supporter happened after Alejando Garnacho scored in the 88th minute until VAR ruled out his goal.

Keane and Richards raced back to see what had happened amid Garnacho's goal being cancelled out following a tight offside call.

The Irishman eventually made his way to the pitchside area after receiving a security escort.

Police are now investigating the alleged assault.

A Sky statement reads: "We understand the police are investigating an alleged assault by a member of the public immediately preceding the footage circulating on social media.

"In the footage seen, Micah Richards was acting to defuse a situation."

London's Met Police added: "Police are investigating following an assault that is alleged to have occurred at the Emirates Stadium during an Arsenal v Manchester United match on Sunday, 3 September."

As for the game, the Gunners recorded a big come-from-behind win over the Red Devils.

Marcus Rashford gave the visitors the lead, but his strike was immediately cancelled out by Martin Odegaard, who slotted home moments later to level.

Declan Rice put his side ahead deep, deep into stoppage time before Gabriel Jesus added a third.