English Premier League sides Manchester United and Liverpool have been charged by UEFA after crowd trouble during the Europa League last-16 second leg on Thursday night.
Rival fans were seen fighting in the stands, seats were thrown and flares were lit at Thursday's 1-1 draw, during which five men were arrested.
Both clubs have been charged with crowd disturbances and throwing of objects.
Liverpool, who won 3-1 on aggregate, have been charged with illicit chants and the setting off of fireworks.
The case will be heard by UEFA's control, ethics and disciplinary body on 19 May, the day after the Europa League final in Basel.
United were not punished by UEFA after some of their fans sang offensive Hillsborough disaster chants during the first leg at Anfield.