Borussia Monchengladbach remain in the race for qualification from Group C after inflicting a first Europa League defeat of the season on Marseille.
It was a lacklustre encounter in Westphalia, with Filip Daems' first-half penalty failing to prompt a meaningful response from Elie Baup's side.
If anything, the French outfit retreated further into themselves and a first loss in seven European outings was confirmed by Peniel Mlapa's long-range effort.
Monchengladbach joined Marseille on four points, with Fenerbahce holding on to top spot by virtue of a 1-0 victory at Limassol.
It took a while for the game to spark into life, but when it did Marc ter Stegen was certainly tested by Loic Remy's wicked shot in the 13th minute.
Remy returned to work the Foals goalkeeper moments later, heading Mathieu Valbuena's corner just past a post before the hosts began to wrest control of the game.
Marseille keeper Steve Mandanda did well to turn away a swerving free-kick from Juan Arango following a cynical foul by Michel Lucas Mendes.
But the France international was picking the ball out of the back of the net in the 32nd minute as Daems converted from the spot after Charles Kabore's handball.
Gladbach's celebrations were muted, though, as Tony Jantschke had to be withdrawn through injury, but the Germans remained in the ascendancy until the break.
Mendes and Alvaro Dominguez exchanged missed opportunities at either end as play resumed.
Marseille came as close to equalising as they would all night when Jordan Ayew nodded Valbuena's sweet cross wide of the target, but the Foals doubled their lead in the 67th minute.
Substitute Mlapa had only been on the pitch two minutes when he rifled home an unstoppable effort from 25 yards.
The young German then sent groans around the Borussia-Park five minutes later when he missed an open goal from six yards.
The incisive Marseille that thumped Limassol 5-1 were nowhere to be seen, and Benoit Cheyrou's aimless drive from distance caused little concern to the hosts as full-time approached.