Two goals in the space of four second-half minutes lifted St. Etienne up to fourth in Ligue 1 as they won at Valenciennes.
Vincent Aboubakar gave the home side the lead in the 69th minute but Pierre-Emerick Aubameyang and Bakary Sono turned things around in a game where both teams were reduced to 10 men in the first half.
The game started badly for the home side with Carlos Sanchez dismissed after a poor fourth-minute tackle on Fabien Lemoine.
The visitors threatened five minutes later through Aubameyang, who saw a shot saved by home goalkeeper Nicolas Penneteau.
However, the numbers were evened up in the 33rd minute when Jean-Pascal Mignot saw red for a foul on Aboubakar.
St Etienne goalkeeper Stephane Ruffier made two good saves in as many minutes, first keeping out a Renaud Cohade effort, before producing an excellent save to deny Aboubakar.
And the home side finished the half on top, with Rudy Mater seeing a left foot shot repelled by Ruffier.
After Ruffier had denied Remi Gomis in the 65th minute, the home side took the lead when Cohade, Gael Danic and Foued Kadir combined to set up Aboubakar, who slotted home.
It was nearly 2-0 two minutes later but Aboubakar struck the bar with a powerful left-foot shot after winning the ball from Sylvain Marchal.
And the visitors made the most of the reprieve as Aubameyang equalised, rounding off good work by Albin Ebondo from close range.
The turnaround was complete four minutes later when Sako tapped in from close range, after Laurent Batlles had struck the post.
Sako hit the bar with a powerful shot in the 82nd minute - and the woodwork denied the visitors again in injury time when Sako lobbed Penneteau.
