The Stade Louis II side were defeated on home soil by Bordeaux and with Lyon also victorious, the championship could go down to the wire.
Lyon continued to keep the pressure on thanks to a 3-1 win against struggling Ajaccio.
Brazilian midfielder Juninho Pernambucano opened the scoring on eight minutes leaving Ajaccio defenders for dead and added a second on 38 with a Gregory Lacombe strike sandwiched in between.
Patrick Muller rounded things off and the result leaves Ajaccio without a win in five and in the relegation places as Montpellier hauled themselves into 16th with a 2-0 win over Troyes thanks to goals from Cedric Barbosa and Geoffrey Doumeng.
Sochaux threw away a two-goal led as they were pinned back to 2-2 at the Stade Bonal against Lille.
The two-goal advantage was thanks to goals from defenders Nisa Saveljic and Maxence Flachez.
Lille pulled it back though through Philippe Brunel and Vladimir Mantchev made sure they shared the points.
Unfortunately the result means Lille fall into one of the relegation places as Sedan snatched victory right at the death against Guingamp to haul themselves out of trouble with a goal from Ludovic Asuar and Alain Liri won the game with just minutes to spare.
Rennes will be pleased to come out of their encounter with Guy Roux's side with a point to their name as they aim to climb away from the relegation dog-fight.
Auxerre were determined to put their midweek Uefa Cup defeat to Liverpool behind them but were unable to breach a dogged Rennes rear-guard.
Nice were also involved in a scoreless draw at the Stade Felix-Bollaert against Lens as they remain in fifth place with 46 points but with several other teams around them also picking up points, the fight for a Uefa Cup place is starting to look very intriguing.
Nantes were impressive at home as they beat struggling Le Harve 2-0 as they continued their good form that has seen them lose just once in their last eight games.
Greg Puyjol's effort on the half hour mark and Marama Vahirua on 90 was enough to secure all three points for Nantes as they continue their rise up the table.
Bastia played out a with a 1-1 draw with Strasbourg. Laurent Batlles was on target for the home side on 13 minutes before Valerien Ismael equalised on 78.
Click here for full match summaries:
Bastia 1-1 Strasbourg
Lens 0-0 Nice
Lyon 3-1 Ajaccio
Monaco 0-1 Bordeaux
Nantes 2-0 Le Havre
Rennes 0-0 Auxerre
Sedan 2-0 Guingamp
Sochaux 2-2 Lille
Troyes 0-2 Montpellier
Click here for French League table
