Police investigating alleged headbutt on Roy Keane

A short video clip of the incident was posted on Twitter on Sunday night.

Police in England are investigating an alleged assault against Roy Keane during Arsenal's clash against Manchester United at the Emirates Stadium on Sunday.

Police in England are investigating an alleged assault against Roy Keane during Arsenal's clash against Manchester United at the Emirates Stadium on Sunday.

There have been reports that a member of the public allegedly aimed a headbutt at the former Republic of Ireland captain shortly after Alejandro Garnacho thought he had won it for United late on.