The enthralling encounter that has always delivered plenty of talking points was at it again, with two late goals separating both sides at full time as Arsenal ran out 3-1 winners.
However, The Athletic reports that the incident with Keane occurred with the game at 1-1, shortly after Man United starlet Alejandro Garnacho thought he had won the game for the Red Devils in its home stretch.
Keane and fellow Sky Sports pundit Micah Richards were travelling between the studio and the pitch when a member of the public allegedly aimed a headbutt at the former Man United midfielder, catching him on the chin and chest.
According to eye witness report, Keane was startled but did not react aggressively, while Richards asked the man to apologise.
However, the confrontation spilt over into a hospitality area, with Richards trying to diffuse the situation before the individual in question fled the scene and left the stadium.
The Metropolitan Police confirmed no arrests had been made, but enquiries were ongoing to identify the perpetrator.
A statement read: “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, September 3.”
A Sky Sports spokesperson added: “We understand the police are investigating an alleged assault by a member of the public immediately preceding the footage circulating on social media.
Arsenal have also stated that they are ‘fully cooperating’ with the authorities, who have launched an investigation since the incident occurred.
The Gunners secured yet another victory on home soil against one of their oldest Premier League foes courtesy of late goals from club-record summer signing Declan Rice and Gabriel Jesus.
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