Arsenal face UEFA charges after their Europa League clash against Cologne was hit by crowd chaos.
Alexis Sanchez scored a second-half screamer to help the Gunners to victory in a match marred by hooliganism.
Kick-off was delayed for an hour after some of the 20,000 German fans broke through security to storm the Emirates Stadium.
There were skirmishes with stewards as Cologne supporters tried to gather in the away section. Police responded by locking down the sold-out 60,000-seater arena and thousands of home and visiting fans were kept waiting outside until 7.45pm.
The match finally kicked off at 9.05pm with riot police with dogs between the German fans and the pitch. Reinforcements arrived to bolster the initial 110 police deployed at the match.
Thousands of Cologne fans were mixed among Arsenal fans all around the stadium.
The Bundeliga’s bottom club were only given 3,000 tickets but up to 20,000 fans are estimated to have made the trip for their first European tie in 20 years.
Police considered calling off the match. Arsenal head of communications Mark Gonnella said: “The decision to go ahead was the best option and the safest option.”
Both Arsenal and FC Cologne face UEFA fines if they are proved to be “negligent” in match preparations or there is “a lack of order or discipline observed inside or around the stadium”. There were initially 110 police at the match but more were drafted in.
Jhon Cordoba scored for Cologne after 10 minutes after a mistake by David Ospina. Sub Sead Kolasinac equalled after the break before Sanchez curled home after a superb invididual run after 67 minutes. Hector Bellerin sealed Arsenal’s victory in their first ever Europa League group game.