Marseille missed the chance to cement their grip on second place in the Ligue 1 table on Saturday as Jorge Sampaoli’s side threw away the lead to lose 2-1 at home to a Brest team on a record winning run.
Brazilian international Gerson gave Marseille a first-half lead at the Velodrome with his second goal in as many games after playing a one-two with captain Dimitri Payet.
However, Brest drew level early in the second half as Romain Faivre scored a penalty awarded for a handball by Boubacar Kamara.
Franck Honorat then crashed a superb winner in off the underside of the crossbar as the side from Brittany made it six successive league wins, the best run in their history in the top flight.
They are up to sixth, while Marseille remain second, 12 points behind leaders Paris Saint-Germain who are in action later on Saturday at Lens.
Kylian Mbappe could be rested for a PSG side already missing the injured Neymar, but Lionel Messi — who won the Ballon d’Or for the seventh time on Monday — should start.
Marseille could drop down the table depending on results elsewhere this weekend, with Rennes and Nice both sitting within two points of the former Champions League winners.