Struggling Gazelec Ajaccio stunned in-form Nice 3-1 on Saturday as the Corsican side secured its first win ever in the French topflight.
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Goals from Gregory Pujol, Roderic Filippi and Damjan Djokovic ended a run of four consecutive wins for the Riviera outfit, the league's best attacking team.
Nice, which scored 17 goals in its past four matches, could not play with its usual pace and gave the ball away too frequently after conceding in the first minute when Pujol put the promoted side ahead with a volley from a tight angle.
Never before had Ajaccio scored three goals in one match in the first division.
Nice leveled in the 12th minute as Filippi beat his own keeper while trying to clear a cross in the box, but he made amends 20 minutes later with a header as the hosts reclaimed the lead. Djokovic then scored from a rebound at the stroke of halftime after goalkeeper Yoan Cardinale denied Amos Youga's volley.
Despite Jerome Le Moigne's sending off in the 87th minute, the hosts held on to the result to move two points ahead of Troyes, which is bottom of the league ahead of Sunday's trip to Bordeaux.
Sixth-place Nice is level on points with Rennes, which held 10-man Lorient to a 1-1 draw with the help of goal-line technology.
Second place Angers drew 0-0 with Guingamp to move within four points of leader Paris Saint-Germain while goals from Ryad Boudebouz and Casimir Ninga gave Montpellier a 2-0 win over Bastia.
Angers was reduced to 10 men for the last 10 minutes of the game after Slimane Sissoko was sent off for a two-footed tackle.
In Lorient, Poland international Kamil Grosicki came off the bench to cancel out Raphael Guerreiro's opener in the Britany derby with a direct free kick that keeper Benjamin Lecomte stopped with a two-handed save in the 68th minute, but replays confirmed the ball had crossed the line.
''With (goal-line technology), once a decision has been taken there is nothing left to argue with,'' said Rennes coach Philippe Montanier. ''Obviosuly I found it great because it played in our favor. If it had been the case, I would still like it.''
It was the first time that a French league goal was validated by the technology introduced this season in France.
Rennes's equalizer came just two minutes after Lamine Kone was sent off for a second yellow card after he held Giovanni Sio. The Rennes forward was expelled too, in the 84th minute for a dangerous tackle.
Rennes remains one point ahead of Lorient and nine points behind PSG, which hosts Saint-Etienne on Sunday.
Portuguese left back Guerreiro put the hosts in front in the 24th minute from Steven Moreira's assist with his first goal this season. Lorient had two more good chances to extend its lead through captain Yann Jouffre and Vincent Le Goff before Sio was fouled by Kone as he raced toward the goal.
The momentum switched to Rennes and Grosicki put the teams level. He came close of adding a second goal with a chip just wide in the 89th minute.