Brest withstood a second-half battering to sneak a 1-0 win over Ligue 1 giants Marseille.
The home side came into the game without a win in four games, but boosted by the knowledge Marseille had not beaten them on their own ground in their previous eight top-flight trips to Brest.
That run was extended as Marseille, who beat Inter Milan in the Champions League in midweek, were brought back down to earth through Paul Baysse's header.
Lille's hopes of retaining their Ligue 1 title suffered another setback when they conceded a last-minute equaliser in a 1-1 draw at Rennes.
The visitors led 1-0 at the break after Aurelien Chedjou converted Eden Hazard's free-kick.
The goal came shortly after Rennes, who had been dominant in the early stages, had been reduced to ten men with Onyekachi Apam sent-off after collecting two yellow cards in quick succession.
However, the ten men conjured up an equaliser in the closing seconds, Mevlut Erding firing a volley past Lille keeper Mickael Landreau. Third-placed Lille are now seven points adrift of leaders Montpellier.
Sochaux slumped to yet another defeat as their top-flight survival hopes suffered a further blow with a 2-0 loss at Toulouse.
The basement boys went behind to Aymen Abdennour's goal in the ninth minute and their fate was sealed when Emmanuel Riviere added a second ten minutes into the next half. It was the fourth game in a row in which Sochaux have not scored.