The Italian side have the same number of points as both Borussia Dortmund and Arsenal and currently sit third, but Benitez does not want his team to start thinking about the permutations just yet.
"We need to focus on this game against Marseille without thinking of the permutations," UEFA.com quotes Benitez as saying. "Of course I would have preferred an easier group in the Champions League, but we cannot change teams. There are no poor sides in the Champions League. It's important that the fans fill the stadium.
"This Marseille team has plenty of quality and is physically strong. Perhaps they are lacking a little in confidence, but we still have to play with the right mindset. We are favourites to win but we must not think about this because Marseille have a few players who can make a difference."
Napoli beat Marseille 2-1 away from home in the last matchday.