Lille have missed the chance to climb to third in Ligue 1 after suffering a 2-1 defeat to Guingamp on Saturday evening.
Rio Mavuba should have put the hosts ahead in just the eighth minute, but he could only fire wide of the target after collecting Sebastien Corchia's inch-perfect pass.
Guingamp were forced onto the back foot for much of the first half as Lille piled the pressure on.
However, it was the visitors who took the lead against the run of play in first-half stoppage time when Sambou Yatabare's inviting cross was headed home by Claudio Beauvue.
Jonas Lossl made a crucial save early in the second half to keep out a curled effort from Corchia as Lille once again threatened to find a breakthrough.
The second goal arrived moments later, but it was Guingamp who dealt another blow to the visitors as Sylvain Marveux spotted the run of Ronnie Schwartz, who slotted in to double his side's advantage.
Michael Frey and Idrissa Gueye both had chances to reduce the deficit, but Lossl was alert once again to frustrate Lille.
Mavuba would finally end Lille's frustration in front of goal with a powerful strike from just inside the box, sparking hopes of a late fightback.
Benjamin Angoua was shown a red card late on for clashing with Nolan Roux, but Guingamp managed to hold on for all three points.
