Seko Fofana and Loïs Openda scored the goal as Lens moved into second place in the Ligue 1 Uber Eats table, leapfrogging Saturday's opponents Marseille with a 2-0 win at the Stade Félix Bollaert-Delelis.
The division's best home record came up against the top away team in this one, with both teams playing in their favoured scenario. Marseille had a point in hand over the hosts at kick-off, meaning everything was in place for a gripping 90 minutes in northern France which promised to potentially decide the chances of one of these two sides to qualify automatically for next season's UEFA Champions League group stage.
Lens had won a league-high 14 times at home this season, but Marseille boasted the best unbeaten run away from home in Europe's top five leagues with 11 games, including nine wins, and the visitors started the stronger. Alexis Sanchez thought he had put them ahead after robbing a hesitant Kevin Danso and rounding Brice Samba, but the Chilean's effort was ruled out by VAR for a foul on the Lens defender (8').
It would have been only the fifth goal Lens had conceded in the first 30 minutes of a match this season, and their escape inspired them to revert to their usual ebullient, well-drilled selves on home soil.
Fofana is the driving force of the team's surprise bid for a top-two finish, and the Lens captain rattled a post with a curling drive (22') before repeating the feat before the break. This time, his well-struck effort again zipped past the dive of Pau Lopez, but found net not woodwork for a superb opening goal (42').
Marseille had picked up a hugely impressive 39 points from losing positions this season, and but for a superb save low to his left by Samba from Jordan Veretout - how did the Lens goalkeeper see the ball arrive at speed through a forest of players amassed in front of him? — Igor Tudor's men would have been level at the break (45+2').
While Sanchez had to be replaced by Vitinha at half-time, Lens re-emerged with the same XI, and more importantly the same intensity and energy that has kept them in the podium hunt all season, and after a brilliant, intricate one-two between Florian Sotoca and Przemyslaw Frankowski, the latter crossed for Openda to head home from close range at the back post (60').
The Belgium international's 19th goal of the league season, which makes him the division's fourth-highest scorer ahead of Sunday's matches, proved doubly valuable when Dimitri Payet pulled one back late on (88') to give OM false hope as they lost second spot with four matches to play.
THE PLAYER: Seko Fofana
The Lens captain was his usual inspirational self, scoring a superb goal. Tireless as ever, his defensive work was as valuable as that when his team were in possession.
THE STAT: 15
Lens have equalled the club record for home wins in a single top-flight season set in 1982/83.