Pape N'Diaye Souare scored six minutes from time to keep Lille hanging onto Paris Saint-Germain's coat-tails with a 1-0 win over 10-man Toulouse on Sunday.
Lille trail the Ligue 1 leaders by four points following the champions' 3-0 win at Reims on Saturday.
The victory puts the pressure on Monaco, who travel to fellow newly-promoted side Nantes later on Sunday, as they now linger eight points off the pace.
The result extended Rene Girard's team's unbeaten run to nine games while Nigerian international goalkeeper Vincent Enyeama has not conceded a goal in 855 minutes of action.
However, it was a largely unconvincing display from the northerners who struggled to create anything despite playing the final 34 minutes with a numerical advantage following Oscar Trejo's red card.
"The sending off totally changed the direction of the match," complained Toulouse coach Alain Casanova.
"When I see my player with three stitches it makes me think there surely must have been a foul beforehand.
"He was given his marching orders and I regret it because we were really causing them problems on the technical front. We found ourselves with ten with half an hour to go and they didn't have many chances."
Enyeama was required to save his side on three occasions from Ben Yedder, Issiaga Sylla and Adrien Regattin.
But Souare found space at the back post from Florent Balmont's cross from the right to head home and snatch the three points.
The Nigerian international goalkeeper admitted his side had luck on their side.
"I made great saves, are you sure?!" he said. "We were lucky because they had a player sent off while they had been playing very well up until that.
"I don't care about statistics. I don't play attention to 'clean sheets'. We've only played 14 matches and there's still a long way to go. Who knows, we could even win the championship. Nothing is impossible."
Meanwhile, around 200 Saint-Etienne fans were evacuated from Nice's Allianz Riviera stadium on the Cote D'Azur following crowd trouble.
The away fans had come under fire from sections of the home support, who had torn up seats and were throwing them at their rival supporters.
Police formed a protective guard around the away fans before evacuating them from the stadium.
According to unconfirmed sources, the bus carrying Saint-Etienne's fans to the ground had been bombarded with stones as it arrived at the stadium.
Even so, the match between Nice and Saint-Etienne kicked off on time at 5pm local time (1600 GMT).