A pitch invader appeared to attack Chris Smalling during Arsenal vs Manchester United .
The fan entered the pitch as the Gunners were celebrating their second goal, when Pierre Emerick Aubameyang had converted a penalty, at the Emirates.
He ran past United defender Smalling and hung his arm out, appearing to make contact with the back of his neck.
The yob then continued his invasion by celebrating with the Arsenal players - before stewards grabbed him and escorted him off he pitch.
The Gunners had taken a first half lead when Granit Xhaka unleashed a long range effort which swerved passed a confused David de Gea.
Aubameyang coolly slotted in a second goal from the spot after Fred had fouled Alexandre Lacazette.
The incident came hours after a Birmingham supporter punched Jack Grealish during the Second City derby.
The Villa star was sucker-punched by the supporter - who came from the home end at St Andrew's - less than 10 minutes after kick-off.
On that occasion the individual was immediately arrested and banned from Birmingham games.
See the invader in Villa game below.
Aston Villa star Jack Grealish PUNCHED IN THE HEAD by a pitch invader