Manchester City have launched an investigation after Aston Villa's goalkeeper was assaulted during a pitch invasion - with Sky pundits Gary Neville and Roy Keane calling the perpetrators "idiots" and "scumbags".
It happened as fans flooded on to the Etihad pitch after City clinched the Premier League title with a remarkable comeback.
Video shows Robin Olsen being touched or slapped on the back of the head by one fan, pushed by another, before a third man apparently hits him in the face - though it's unclear if it was intentional.
Olsen is "completely fine" but did take a "bang on the back of the head," said Aston Villa - who regard the matter as closed and won't be making a complaint.
It follows other recent pitch invasion incidents, including a fan who was jailed for headbutting Sheffield United's Billy Sharp, and Crystal Palace manager Patrick Vieira involved in an altercation with an Everton supporter.
Former Manchester United stars Neville and Keane said it was deeply concerning.
"Running on the pitch is obviously delirious - they've won the league - so I get that," said Neville.
"But attacking the opposition players on the pitch, where has this come from? Why is it happening?... It's absolutely ridiculous."
Keane, who played alongside Neville at Manchester United, called it a "disgrace" and suggested someone could even "do something silly like stab a player".
"A player or a manager is going to be seriously injured," he said.
Manchester City said it wanted to "sincerely apologise" to Olsen.
"The Club has launched an immediate investigation and once identified, the individual responsible will be issued with an indefinite stadium ban," it said in a statement.
The FA will also be investigating and said it was "very concerned about the rise in anti-social behaviour from fans as we reach the end of the season".
"Clubs play a vital role in addressing this issue and they need to prevent pitch invasions from occurring, as well as taking their own action against those that break the rules and the law," it said.
"The FA will be seeking to do all that it can to work with clubs as well as addressing the issues from a disciplinary perspective."
UPDATE:
Two football fans have been charged following Manchester City's Premier League game with Aston Villa at the Etihad Stadium on Sunday.
Phillip Maxwell, of Anzio Row, Knowsley, has been charged with throwing a missile (pyrotechnic) onto the pitch and will appear at Manchester and Salford Magistrates' Court today.
Paul Colbridge, of Whitegate Drive, Salford, has been charged with going onto the pitch and will appear at Manchester and Salford Magistrates' Court on 7 June 2022.
Both have been bailed ahead of the court appearances.
Separately, police said enquiries into the reported assault of a player on the pitch after the final whistle are ongoing with officers working in partnership with both football clubs.
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