Lille was the only top four Ligue 1 side to win its most recent match, and has turned a stretch of four wins in its last five into a realistic shot at the top spot in the table.
Lille snapped a more than five decade title drought last season with its first title since 1954, and sits just seven points off the top with six matches left in the season ahead of Saturday's trip to Dijon.
While leader Montpellier lost its most recent fixture, second-place PSG settled for a draw, and fourth-place Lyon lost, the defending champions downed Ajaccio, 4-1, to stir up the title race.
"This is a win that could count at the end," Lille coach Rudi Garcia said.
Although Lille has a sizable deficit to overturn, it still has matches against PSG on April 29 and at Montpellier on the final weekend of the season.
Garcia's club holds the third Champions League qualification spot, so there is not much pressure on his side entering the homestretch. But with the top within sight, Lille could easily earn a surprise repeat.
Dijon has lost two straight matches and sits among six clubs separated by just two points from 14th to 19th in the standings. With relegation a possibility, the 16-loss team cannot afford to drop many more points this season.
Montpellier should feel the same way, if it intends to finish off a memorable season with its first Ligue 1 title.
"There's not a lot to say - we'll have to pick ourselves up again," Montpellier coach Rene Girard said after a 2-1 loss to Lorient last week, "and take another look at ourselves."
Montpellier also plays Saturday, at home against a Valenciennes side that sits just four points above the relegation zone.
PSG started the season as the clear favorite to win its first title since 1994, but even with over $100 million in transfers between the summer and winter, it has been a tough recent stretch for new coach Carlo Ancelotti.
The Paris club has lost just one of its last five Ligue 1 matches, but has just one win during that stretch as well.
"I think that we have a problem in terms of determination and concentration," Ancelotti said after a 1-1 draw with Auxerre. "We're taking things too easily. If we want to win the league, we can't play like that."
PSG hosts 18th-place Sochaux on Sunday, as it also faces a team with survival to play for late in the season as well.
Fourth-place Lyon, which has slipped out of the Champions League chase, hosts Lorient on Sunday. Lyon leads Toulouse, which visits Evian on Saturday, only by goal differential for a Europa League spot. Lorient is another team also still in the relegation fight, as it sits 13th but just two points from danger.
Also Saturday, relegation-threatened Brest hosts Europa hopeful Rennes, relegation-threatened Caen hosts Europa hopeful St Etienne, Nice hosts Auxerre in a relegation clash, and Bordeaux and Marseille meet as mid-table sides. Ajaccio, 19th on 33 points, hosts mid-table Nancy in Sunday's other match.