Both Borussia Dortmund and Liverpool have been charged by UEFA over offences committed by fans during their Europa League quarterfinal first leg in Germany on Thursday.
European football's governing body confirmed that disciplinary proceedings have been opened against the clubs.
Dortmund have been charged over stairways being blocked, while Liverpool face a charge in relation to their supporters letting off fireworks at Signal Iduna Park.
The cases will be dealt with by UEFA's control, ethics and disciplinary body on May 19, the day after the Europa League final is played in Basel.
Liverpool already face charges over fan chants, fireworks being set off, objects being thrown and more general crowd disturbances after the second leg of the previous round against Manchester United at Old Trafford.
United have also been charged over crowd disturbances and the throwing of objects, in addition to blocked stairways.
UEFA are still investigating claims that chants about Hillsborough and Munich were sung by rival fans at both Anfield and Old Trafford during the round-of-16 tie, and further charges could follow.