ARSENAL fans vented their fury on social media after Sporting Lisbon star Sebastian Coates escaped unpunished after his headbutt floored Stephan Lichtsteiner.

The Gunners’ 11th victory in a row was marred by bitter drama at the end as Uruguay defender Coates approached the Arsenal full-back and sent him flying.

TV cameras caught what looked a blatant assault from Coates, whose blunder had handed Danny Welbeck a deserved 77th minute winner in this Europa League clash.

But Arsenal supporters were baffled at how officials seemingly failed to spot Coates thrusting his head into Lichtsteiner’s - in the middle of the penalty area.

One fan tweeted: “Wonder what match @europaLeague officials are watching where they completely miss Coates headbutt on @lichtsteinerSte.”

Another said: “Tough game for Arsenal, but we did it. 5 referees, but still couldn’t spot a headbutt from Coates on Lichtsteiner. Job done lads.”

Supporters also called for TV evidence to land Coates in hot water.

One argued: “Surely a retrospective ban for Coates@ Definite headbutt on to banned after TV footage is studied. Definite headbutt on Lichtsteiner.”