Saint-Etienne took sole possession of third place in Ligue 1 after 10-man Lyon faltered at Stade Reims on Sunday.
Christophe Galtier's men claimed a narrow 1-0 victory over lowly Evian Thonon Gaillard at Stade Geoffroy-Guichard.
Saint-Etienne scored the match-winning goal 12 minutes from time, when Evian goalkeeper Bertrand Laquait turned the ball into his own net.
Francois Clerc whipped in a cross to the back post, picking out midfielder Romain Hamouma.
The former Caen man headed the ball towards goal and his effort hit the underside of the crossbar, and received a helping hand as Laquait failed to keep it out.
Saint-Etienne move into third on goal difference, ahead of Lyon, who suffered a surprise 1-0 loss to Reims.
Lyon were looking to end a four-game winless run but their hopes of doing so were dented when Milan Bisevac gave away a penalty and was sent off as a result.
Grzegorz Krychowiak converted the spot-kick, handing Reims their third successive home victory after trumping Rennes and leaders Paris Saint-Germain in recent weeks.