It was after the final whistle that Arsenal's goalkeeper got into an argument with Tottenham's Brazilian World Cup player Richarlison.
There was an upset atmosphere even in the stands when Ramsdale collected his stuff behind the goal.
A man then ran down towards the goalkeeper and kicked him in the back, causing a bigger fight between several players to break out.
Arsenal coach Mikel Arteta has palpably withdrawn his hottest players.
- The supporters were on me during the match, so I gave back.
The ones I gave back to took it sportsmanship, but one supporter tried to slap me in the back.
It's a shame, because it's just a football game after all, said Ramsdale, according to the BBC.
Was banned outright by Tottenham
The man has now been identified and charged with assault by kicking and throwing an object.
Police have been assisted by Tottenham, who strongly distance themselves from the attack, in their efforts to identify the man named in the English press.
New images from earlier today show how the man took off his mask and exposed his face.
The man was immediately banned from Tottenham Hotspur Stadium.
Arsenal won the match 2-0 and have gone clear at the top of the Premier League.