Kevin Monnet-Paquet scored a ninth-minute opener at Saint-Etienne's Stade Geoffroy Guichard and Romain Hamouma slotted in a second on 22 minutes as Les Verts closed to within a point of fourth-placed Lyon.

The visitors finished with nine men as substitute Rachid Ghezzal and Corentin Tolisso were dismissed in stoppage time to further sour a dreadful evening for Lyon.

"It was a negative result and the behaviour was unworthy of a derby notably in the first half," complained Lyon coach Bruno Genesio of the fiery clash. 

"All defeats are difficult but it's even harder to swallow in a derby because pride is at stake."

Saint-Etienne, who face Manchester United in the Europa League last 32 this month, have won three games in a row in Ligue 1, while Lyon's Champions League hopes look doomed after falling 12 points behind the top three.

"This was surely our best start since the beginning of the season and just what was needed in a derby," said Saint-Etienne coach Christophe Galtier. 

"There was a lot of determination, with a collective force. The players really went after this victory."

Both sides suffered French Cup last-32 exits in midweek, although Lyon were boosted by the return from injury of leading scorer Alexandre Lacazette.

But an early defensive blunder from Emanuel Mammana proved fatal for Lyon as Saint-Etienne won back possession on the edge of the area with Monnet-Paquet firing through the legs of Anthony Lopes.

Tolisso headed against the crossbar after he was left unmarked from a Nabil Fekir cross, but a rash decision from Lopes resulted in the hosts grabbing a second goal shortly after.

The Lyon goalkeeper raced out of his box to try and cut out a through ball but lost out to Hamouma, who calmly skipped round the Portugal international to double Saint-Etienne's lead.

With the visitors heading towards a third straight loss to Saint-Etienne at Le Chaudron (The Cauldron), Lyon capitulated in the closing stages as Ghezzal picked up two yellow cards in quick succession before Tolisso saw red for a wild lunge at Fabien Lemoine.

On Saturday, Monaco moved three points clear at the top of the table with a 3-0 victory over title rivals Nice.

Valere Germain opened the scoring at the Stade Louis II before Radamel Falcao struck twice as Nice lost for just the second time this season.
Paris Saint-Germain climbed above Nice into second on goal difference after winning 3-1 at Dijon.

Lucas struck first in Dijon, but the hosts equalised just two minutes later through Julio Tavares.

Thiago Silva then bundled in from a corner on 81 minutes, while Edinson Cavani grabbed his 22nd goal of the campaign to secure victory.