Arsenal boss Arsene Wenger believes it would be "completely unfair" for the club to be hit with sanctions following Thursday night's Europa League clash against Cologne.
UEFA announced on Friday morning that they had opened disciplinary proceedings following the crowd trouble which overshadowed the match between the two sides at the Emirates Stadium.
The Group H tie, in which Arsenal eventually ran out as 3-1 winners, was delayed by an hour as ticketless Cologne fans looked to gain entry to the ground.
The visitors were issued with 3,000 tickets, but around 20,000 Cologne fans are believed to have made the journey to London.
There were clearly thousands of away supporters sitting among Arsenal fans, causing a security risk.
Five arrests were made over the course of the evening and Arsenal issued a statement on Friday insisting the safety of supporters was the main concern at the time as the Premier League club "launched a full review" of the events.
Later in the morning UEFA confirmed they had opened proceedings against both clubs. Cologne's charges included crowd disturbances, setting off fireworks, throwing of objects and acts of damage by the Cologne fans, while Arsenal face a probe for "stairways blocked in away supporter sector".
Speaking before UEFA's ruling, Wenger said Arsenal had done everything possible to manage the situation and should not face ramifications.
"It would be completely unfair," he told Sky Sports News.
"I think we prepared well before the game to stop people who are not Arsenal members to buy tickets.
"Overall, from what I've heard, most of the problems came from touts selling tickets outside the stations. We are completely open to having an enquiry but on our side I think we worked very hard to organise the game well."
The Arsenal boss, who takes his side to face Premier League champions Chelsea on Sunday, admitted he was almost certain the game would be postponed as police and event staff battled to get the crowds under control.
"Last night was a bit special because the kick-off was delayed and we didn't even know if we would play or not," he added.
"At some stage it looked like 90 per cent it would not take place. I thought the security would never take a gamble on creating some problems.
"To cancel the game could be worse outside the stadium. But overall we waited patiently in the dressing room and prepared for the game."