UEFA has opened disciplinary proceedings against Cologne and Arsenal following crowd disturbances prior to the Europa League clash at the Emirates Stadium on Thursday.
The German club face four charges, including crowd disturbances and setting off fireworks while the Gunners face a charge over blocked stairways.
The game was delayed by more than an hour as thousands of away fans arrived at Emirates Stadium without tickets.
Around 20,000 Cologne fans arrived in London despite the German club being given a ticket allocation of 2,900.
This case will be dealt with by the Uefa Control, Ethics and Disciplinary Body on 21 September.
