Lille can knock fourth-place Lyon out of the title race on Sunday when the French league leaders face the seven-time champions at home.
Lyon trails Lille by four points, with second-place Rennes and Marseille in between.
"It's a turning point for Lille," Lyon fullback Anthony Reveillere said, "because if they win, they know they will eliminate a title contender."
Lille, which has lost only once at home this season, will rely on the most lethal attack in the league with Ivory Coast forward Gervinho and Senegal striker Moussa Sow, who have combined for 27 goals.
But the club's 13-game unbeaten run ended last weekend in a 1-0 loss at Montpellier.
"We were no longer used to not taking points," Lille coach Rudi Garcia said. "We'll have to refocus and make sure everybody does more because we didn't see a team leading the league and doing anything to take points."
Lyon has won its last two league games, scoring four goals in each of them.
"There's some chemistry within the squad," Lyon coach Claude Puel said. "It shows the quality of our squad and its mindset. If we keep that mindset, we can do some very good things until the end of the season."
Lyon striker Lisandro Lopez is doubtful for the Lille match after picking up a hamstring injury in training last week.
But Lyon will count on forward Bafetimbi Gomis to lead the offense. Gomis scored the equalizer Tuesday in Lyon's 1-1 draw with Real Madrid in the Champions League.
A victory from Lyon could allow Rennes to take over at the top and let third-place Marseille go level on points with Lille.
Marseille was held to a goalless draw by Manchester United on Wednesday in the Champions League.
"The French league is our priority," Marseille coach Didier Deschamps said. "We're in a period where we must rack up the maximum number of points. The other teams are taking points. We must stay in the leading pack."
Marseille has won its last three league matches, but the defending champions will miss Andre-Pierre Gignac for Sunday's match at Nancy. The Marseille forward injured his groin last weekend.
Rennes has emerged as a dark horse in the title race, trailing Lille by only two points. But Rennes coach Frederic Antonetti downplayed expectations on his young squad.
"Let's be reasonable. There are teams that are more seasoned than us," Antonetti said after his team's 2-1 win over Toulouse last weekend. "Youth compensates for inexperience with a great generosity. This team shows desire and solidity in every match. But let's wait until the end of March to state what our ambitions are."
Rennes has built its success on a tight defense, the best in the league with only 18 goals conceded in 24 matches. But its offense ranks only 11th in the league with 28 goals scored.
On Saturday, Rennes will host Lens, a team fighting relegation.
"I'm really frustrated to see that my club is not going well," Lens defender Alaeddine Yahia said. "I want the club to be safe. It's painful to see us in that situation."
Also Saturday, it's: Arles-Avignon vs. Brest; Monaco vs. Caen; Saint-Etienne vs. Nice; Sochaux vs. Montpellier; Valenciennes vs. Lorient; and Bordeaux vs. Auxerre.
On Sunday, fifth-place Paris Saint-Germain hosts Toulouse.
