Lens' relegation to Ligue 2 was confirmed by a 1-1 draw at Monaco.
Raphael Varane struck a last-gasp equaliser for the visitors, cancelling out Benjamin Moukandjo's 15th-minute opener, but it was not enough for Lens. The result saw them slip seven points behind fourth-bottom Nancy - who were 3-0 winners against fellow strugglers Nice - with two games remaining.
Youssouf Hadji, Pascal Berenguer and substitute Bakaye Traore were the men on target as Nancy boosted their survival hopes, aided by the second-half dismissal of Renato Civelli. Nancy's victory moved them out of the drop zone at the expense of Monaco.
At the other end of the table, out-of-sorts Rennes secured Europa League qualification with a 2-1 win at St Etienne which severely dented the hosts' hopes of European football.
Victor Montano's early strike had the visitors ahead and Jerome Leroy restored their advantage just before half-time after Bakary Sako had restored parity.
Marseille and Lorient cancelled each other out with a 2-2 draw on a night when Ligue 1 leaders Lille were the real winners.
A late equaliser from Andre-Pierre Gignac earned second-placed Marseille a point, but they now stand three points behind the front-runners and have only two games remaining. Lille have three to play, and with a superior goal difference a victory over Sochaux on Wednesday will make them champions
Back at the bottom, Caen climbed three points clear of the relegation zone with a 2-0 home win over Montpellier thanks to goals from Romain Hamouma and substitute Kandia Traore.
A late equaliser denied Valenciennes the win that could have all but assured them of their Ligue 1 status as they drew 1-1 with fellow relegation battlers Auxerre.
It was against the run of play that the hosts took an 80th-minute lead through Foued Kadir, but three minutes from time Jo-Gook Jung headed home the leveller.
Toulouse also blew another golden chance to secure their survival as Kamel Ghilas' 20th-minute strike handed relegated Arles a 1-0 triumph - only their second win of the season in Avignon.