Arsenal manager Arsene Wenger has called on Uefa to investigate the actions of Cologne fans before and during the Europa League tie at The Emirates Stadium. An estimated 17,000 German fans managed to obtain tickets for the game which the Gunners won 3-1, despite the club's allocation being nearly a sixth of that figure.
Supporters of the Bundesliga club congregated in London ahead of the game and attempted to power their way into the Emirates ahead of kick-off, forcing the start to be delayed by 90 minutes. Once inside the ground, it was immediately clear many away followers had purchased tickets in home areas of the stadium in what soon became an expanded visitors section.
Visiting fans clashed with stewards in an attempt to break into the away end before riot police were enlisted to keep Cologne followers away from Arsenal fans, who were becoming increasing bewildered by the events. Flares were twice lit during the 90 minutes, including after Jhon Córdoba gave Peter Stoger's side a shock first half lead.
Goals from substitute Sead Kolasinac, Alexis Sanchez and Hector Bellerin gave the Gunners victory on the night, but the match was overshadowed but the incidents before the during the game. Four people have been arrested for public order offences, but Wenger wants to see European football's governing body take action.
"They have to analyse the facts of what happens," he told reporters. "They will certainly make an enquiry into seeing what happened for sure. "They were very clever I don't know how they managed to infiltrate our fans and they got everywhere. They did that very well. I do not know whether they went through Arsenal membership or internet but they did very well.
"Cologne has not played in Europe for 25 years. In the first night they go out they spoil their night and I couldn't understand that, I couldn't get around that. Were the problems created by the people who had no tickets? I don't know. Certainly they had more people here than tickets so that was certainly the cause. I'll leave that to the police. I only had to decide if the game is not played what do we do?"
Following the hour delay, the match was in some doubt as Cologne fans appeared to significantly outnumber security staff including in the North Bank end of the The Emirates. Wenger says the police's decision to play the fixture was a "risk" and admits he had already begun constructing a contingency plan.
"What was difficult for me was that I had all kinds of plans to think about," the Frenchman added, whose Arsenal side face Chelsea this weekend. "Do we play tomorrow? What time do we want to play? Do we play next week? They had a Bundesliga game next week, we have the League Cup midweek as well. Do we move it Tuesday and play Thursday? It was all kinds of speculation that we had to analyse and see how we can deal with the situation.
"At some stage I thought they would not play the game because I couldn't see the police taking any risk. We live in a society with 100% security I thought they would never take a gamble to play this game when I saw the images around the stadium. Our supporters dealt well with the situation as well and I hope everything goes well after the game. If nothing happens after the game then yes [it was the right decision]."