After trouble in their respective Europa League games on Thursday, UEFA has opened disciplinary proceedings against Marseille and Lyon.
Arsenal face a trip to CSKA Moscow in the Europa League quarter-finals, while favourites Atletico Madrid take on Sporting CP.
CSKA Moscow edged a thriller to knock Lyon out of the Europa League on the away goals rule following a 3-3 aggregate draw in their tie.
Another disappointing display ended Borussia Dortmund's Europa League hopes as they were knocked out by Red Bull Salzburg.
Hakan Calhanoglu gave AC Milan the lead at Emirates Stadium, but Danny Welbeck scored either side of Granit Xhaka to see Arsenal through.
Lucas Ocampos' brace led Marseille to a confident victory over Athletic Bilbao in their Europa League meeting at the Stade Velodrome.