Relegation-threatened Monaco surprisingly beat 10-man Lille 1-0 on Saturday to end the French league leader's four-game winning streak and give Marseille a chance to make up ground in the title race.
Second-place Marseille could cut Lille's lead to one point if it beats Toulouse on Sunday.
South Korea forward Park Chu-young scored for Monaco in the 12th minute after intercepting a backpass from Lille center back Adil Rami to round goalkeeper Mickael Landreau and slot into an empty net for his 11th goal this season.
"We didn't play with our hearts," Rami said. "There are two or three things that were not right. We will clear the air between us in the dressing room."
Lille was down to 10 men in the 37th after Ivory Coast forward Gervinho was fouled by Adriano and retaliated by shoving the Monaco defender.
Monaco moved out of the relegation zone with the win.
"We wanted to show all the clubs in the French league that we could beat the big teams," Monaco coach Laurent Banide said. "Tonight we saw a Monaco team that gave its everything. We won with our guts."
"But there's still a long way to go. Let's not forget that our goal is to be safe."
Also Saturday it was: Caen 1, Paris Saint-Germain 2; Brest 2, Rennes 0; Auxerre 2, Saint-Etienne 2; Bordeaux 0; Arles-Avignon 0; Lorient 1, Sochaux 1; and Valenciennes 1, Nancy 1.
PSG midfielder Christophe Jallet volleyed home a cross from Nene in the 13th before Clement Chantome doubled the lead from a tight angle with a powerful strike into the top corner in the 69th. Romain Hamouma scored a consolation goal for Caen in the fourth minute of stoppage time.
PSG remained in fifth place but narrowed the gap to fourth-place Lyon to one point.
"The goal was to win because it's been a long time since we last got a taste of victory," Chantome said. "It's good for the team and the confidence of the squad."
PSG snapped a four-game winless run.
In Brest, Nolan found the net with a long-range strike into the top corner in the 29th. Bruno Grougi added a second goal for the hosts in the 55th.
Rennes missed an opportunity to go level on points with Marseille.
Lyon just needs a draw with Lens on Sunday to leapfrog Rennes into third place.
In Auxerre, Dariusz Dudka salvaged a draw for the hosts by converting a penalty in the 80th after Poland forward Ireneusz Jelen was fouled inside the area.
France international Dimitri Payet played in Emmanuel Riviere, who beat goalkeeper Olivier Sorin to put Saint-Etienne ahead in the 27th, but Auxerre striker Dennis Oliech equalized in the 42nd with a low shot from the edge of the box. Pierre Aubameyang then took a pass from Emmanuel Riviere to give Saint-Etienne a 2-1 lead in the 70th.
Auxerre fell into the relegation zone despite the draw.
In Bordeaux, Felipe Andre made his first start for the hosts after coming off the bench seven times this season. But the Brazil international, still chasing his first goal in the French league, was ineffective and was replaced by forward Cheikh Diabate in the 59th.
In Lorient, defender Jeremy Morel produced a nice effort on his left flank to level in the 35th after Sochaux fullback Boukary Drame had opened the scoring in the 25th by heading home a corner from Ryad Boudebouz.
In Valenciennes, Gregory Pujol gave the hosts the lead in the 43rd, heading in a corner to raise his tally to 13 goals this season.
But Nancy substitute Marama Vahirua denied Valenciennes victory by curling home a free kick in the third minute of injury time.
Valenciennes defender Milan Bisevac was dismissed in the 39th after picking up a second yellow card.
Nancy also had to play with only 10 men after the 59th when Michael Chretien earned a second yellow card.
On Sunday, Nice visits Montpellier.
