Brest are on the brink of relegation after defeat.
Sochaux moved onto the edge of safety in Ligue 1 as they beat bottom placed Brest 0-2.
The home side are now staring relegation straight in the eye as they are six points of safety, after two goals from Sloan Privat sank the hosts.
Privat netted his first just after half time, before bagging a brace following the dismissal of Brest player Florian Lejeune on 77 minutes.
The three points means the visitors are as good as safe in the division on 40 points.