Arsenal and Bayern Munich have been charged by Uefa following the behaviour of their fans in Tuesday’s Champions League last-16 tie at the Emirates.
Bayern have been charged with the throwing of objects after their supporters delayed play by launching rolls of paper onto the pitch.
The visiting fans were protesting over ticket prices.
Arsenal also face charges after a supporter invaded the field during their crushing 5-1 second-leg defeat.
Disciplinary proceedings have also been opened against Napoli following their 6-2 aggregate loss to Real Madrid at the Stadio San Paolo on Tuesday.
The Italian club have four charges against them; the use of a laser pointer, blocking stairways, throwing of objects and setting off fireworks.
All cases will be dealt with by UEFA on 23 March.