UEFA have opened "disciplinary proceedings" against Arsenal for the late kick-off and pitch invasion during the Europa League match against Qarabag on Thursday.
As reported by Matthew Treadwell of Sky Sports, a visiting fan entered the pitch late waving a political flag. The match also started three minutes late.
The Gunners aren't the only club to run into trouble after the matches on Thursday, as UEFA announced separate proceedings against AC Milan, Eintracht Frankfurt and Olympiakos via their official site.
The cases against those clubs will be dealt with by the UEFA Control, Ethics and Disciplinary Body on January 10, while Arsenal will have to wait until February 21 for the outcome of their case.