Lens defeated Marseille 2-1 on Saturday to move to second place in Ligue 1 and pile the pressure on crisis-hit leaders Paris Saint-Germain whose lead was cut to three points.
The victory was Lens' 15th at home this season in the league against just one defeat and one draw.
Marseille slipped back to third in the table, five points behind PSG.
Skipper Seko Fofana opened the scoring for Lens after 42 minutes with a powerful, long-range shot before Lois Openda headed in the second on the hour mark.
"It's magnificent, I have no words. It's deserved, but there are still four games left to get as high as possible in the table," said Lens goalkeeper Brice Samba.
"Given what we've shown since the start of the season, this is no coincidence and that's good for us. Our coach (Franck Haise), he's the best, he's got it all figured out."
Dimitri Payet gave Marseille hope of getting something from their 800km trip north with a goal in the 88th minute but Lens held on.
"In football, there is no question of merit, it doesn't matter who deserves to win, the important thing is victory," said Marseille coach Igor Tudor who criticised the referee for not sending off Lens' Facundo Medina for kicking the ball at the bench.
Marseille were also incensed that an Alexis Sanchez goal in the eighth minute was chalked off for a foul on Kevin Danso despite there appearing to be minimal contact.
"I told the referee at half-time that he had the courage to rule out a goal but not to give a second yellow card to Medina," said Tudor.
Both Lille and Rennes saw their push for European places stall.
Lille slipped to a 1-0 defeat at Reims with Marshall Munetsi scoring the only goal in the 21st minute. Lille remain in fifth place with 59 points.
"All the matches that we don't win are frustrating," said Lille coach Paulo Fonseca.
Will Still, the coach of Reims, admitted his own game plan had left himself baffled.
"This system has no name," he smiled after halting a three-match losing streak. "It was a risk worth taking, I was tired of losing."
Sixth-placed Rennes were beaten 2-1 in Nice for whom Gaetan Laborde and Terem Moffi were on target in the 50th and 72nd minutes as their team secured a first home win since February 10.
Benjamin Bourigeaud's 78th-minute strike was too little, too late for Rennes who are sixth in the table