UEFA has opened disciplinary proceedings against Arsenal and Bayern Munich for their supporters' conduct during their Champions League round of 16 clash on Tuesday.
European football's governing body investigated either fan bodies' respective roles in a pitch invasion and the throwing of objects onto the field at the Emirates Stadium.
Bayern had repeated their first-leg showing in the last-16 tie with a 5-1 win in the return meeting on a miserable night for the London club.
The match was forced to a brief halt early on, though, as Bayern fans hurled rolls of toilet paper onto the pitch in protest at the ticket prices set by Arsenal.
The Gunners also face action after one of their supporters was spotted running onto the playing surface just before the end of the match.
UEFA's Control, Ethics and Disciplinary body will deal with the cases on March 23, with Napoli also set to be investigated for the blocking of stairways, use of a laser pointer, the throwing of objects and setting off of fireworks in their 3-1 defeat by Real Madrid.