Napoli coach Rafael Benitez has brushed off Marseille's apparent struggles and says it will be 'critical' to beat the French side if his team is to qualify for the Champions League knockout phase.
Napoli host Elie Baup's men on Wednesday, a fortnight after claiming a precious 2-1 victory in France to pull level with Group F leaders Arsenal and second-placed Borussia Dortmund on six points.
With Marseille still to pick up any points after three games, their bid for a place in the last 16 is virtually over.
For Napoli there is everything to play for, but with a trip to Dortmund up next and the Italians ending their group campaign by welcoming Arsenal to the San Paolo on December 11, Benitez is keen to avoid any slip-ups.
"It's going to be a very important game for us," Benitez told Eurogoals.
"Especially since we have Borussia Dortmund and Arsenal coming up.
"It's going to be a real challenge to qualify , so it's critical that we beat Marseille. It is true that they are going through a difficult period, but they have quality in their squad.
"We can't relax and think it'll be easy. That would be unforgivable."
Napoli are back in the competition after former coach Walter Mazzarri, now at Inter Milan, steered the Partenopei to a second-place finish in Italy's Serie A last season.
And thanks to the positive start made by Benitez, whose well-rounded squad includes the attacking talents of Gonzalo Higuain, Marek Hamsik, Lorenzo Insigne and Jose Callejon, Napoli sit second, five points adrift of leaders Roma.
Marseille, meanwhile, are enduring one of their worst seasons to date and only ended a five-game losing streak with a 1-1 draw at Rennes on Saturday when captain and goalkeeper Steve Mandanda saved a spot kick.
Napoli should field a full-strength side for Wednesday's match, although Benitez will have to do without right-back Giandomenico Mesto, who has been sidelined with knee ligament damage.
Mesto suffered the injury in Saturday's win over Catania and is set to be out for several months.