Lille had to settle for a 1-1 draw after being pegged back by Bordeaux, opening the door to the chasing pack in the race for the Ligue 1 title.
The leaders survived fierce early pressure and led through Moussa Sow's strike shortly before the hour mark as they looked to stretch their advantage over Marseille and Lyon. But defender Vujadin Savic equalised for Les Girondins, who nevertheless slipped below Sochaux to 10th in the table.
Rennes' faltering title bid suffered a further setback as they lost 2-1 at home to Lorient.
Stephane Dalmat put the hosts ahead midway through the first half but the game turned in the visitors' favour six minutes before the break when Rennes midfielder Samuel Souprayen was sent off for a second bookable offence.
The visitors took full advantage of their extra man and turned things around after the interval through goals from Kevin Gameiro and Francis Coquelin to leave fourth-placed Rennes without a win in their last five league matches.
The home team's misery was compounded four minutes from time when the dismissal of Jean-Armel Kana-Biyik saw them reduced to nine men.
St Etienne overturned a half-time deficit to record a 2-1 victory which leaves opponents Nancy in the thick of the relegation scrap.
Andre Luiz gave the visitors the lead six minutes before half-time, but Dimitri Payet's quickfire brace turned the game on its head. Dariusz Dudka scored a stunning stoppage-time free-kick to hand Auxerre a much-needed 1-0 win at Toulouse which moved them out of the drop zone.
The visitors started the weekend third from bottom but their third win from six matches means they have plenty of momentum heading into the final weeks of the season. They left it late at the Stade Municipal with Dudka powering a wonderful free-kick past home keeper Mathieu Valverde in the 92nd minute.
Caen slipped into the bottom three with a 3-2 defeat to a Sochaux side who now look assured of their place in Ligue 1 next season.
Youssef El Arabi gave the visitors the lead but Sochaux hit back with goals from Boukary Drame and a Modibo Maiga double. Although Romain Hamouma netted in the closing minutes, the Normandy side were unable to find an equaliser.
Lens' hopes of avoiding the drop were dealt a blow as Brest forced a 1-1 draw at the Stade Felix Bollaert thanks to an equaliser from Jonathan Ayite.
Lens began the game seven points adrift of safety and were in control when Adil Hermach netted 20 minutes in. But Ayite equalised with half an hour to go for a point which is more help to Brest's hopes of avoiding the drop.
Nice eased their relegation worries with an exciting 3-2 victory that sent Monaco ever closer to the drop zone.
Anthony Mounier and Jean-Jacques Gosso traded goals in the opening half-hour to make it 1-1 at half-time before Renato Civelli and Eric Mouloungui opened a two-goal buffer for the hosts.
Park Chu-young converted a 76th-minute penalty to set up a tense finale but Nice held on, leaving them in 12th and Monaco level with third-bottom Caen.