Ghana winger Andre Ayew scored for Marseille on Friday night but the Olympians dropped more points in the Ligue 1 title race as they surrendered a two-goal lead to lose 3-2 to Caen at the Stade Velodrome.
Goals from Andre Ayew and Andre-Pierre Gignac helped Marseille recover from an early penalty miss and put them on course to regain second place in the table.
However, Nicolas Seube and Emiliano Sala struck within two second-half minutes before Nicolas Benezet scored a late winner to cap a famous fightback.
It should have been a dream start for the hosts as Michy Batshuayi earned a second-minute penalty under the challenge of Alaeddine Yahia, only to have his spot kick saved by Remi Vercoutre.
The Belgian squandered a couple more decent chances as Marseille initially failed to make their first-half dominance pay, with Florian Thauvin and Lucas Ocampos also going close either side of Ayew hitting the post.
Ayew was the man who finally got the breakthrough as he thumped into the bottom corner on the stroke of half time,
Marcelo Bielsa's team seemed on their way to a 12th home win of the season, but Seube converted Thomas Lemar's cross at the back post on 68 minutes and Sala soon equalised with his second in as many games.
The striker, who been denied at point-blank range by Steve Mandanda in the first half, calmly tucked beyond the France goalkeeper from inside the box after N'Golo Kante supplied him to finish a swift counter-attack.
Marseille sought a response as Thauvin and Ayew sent shots off target, but they were dealt an even bigger sucker punch when Benezet curled into the top corner from the edge of the box to snatch Caen three unlikely points.
A fourth game without a win, three of which half been against bottom-half sides, leaves Bielsa's men four points adrift of leaders Lyon and third behind Paris Saint-Germain, while Caen climb five places to ninth in the table.