The hosts came into this game knowing they had to win to guarantee their top-flight status for another season, with Nantes ready to seize upon any errors with a victory over Angers.
Auxerre nearly fell behind inside the opening five minutes when Lois Openda picked out the onrushing Alexis Claude-Maurice, but he was denied by Ionut Radu.
Pelissier’s men seemed fortunate to avoid conceding a penalty in the build-up to that chance, as Isaak Toure appeared to block Deiver Machado, but there was no VAR review.
Down the other end, Nuno da Costa headed wide from Akim Zedadka’s cross ahead of a sobering 60 seconds for Pelissier’s team. Ignatius Ganago gave Nantes a priceless lead against Angers, before Claude-Maurice broke the deadlock for the Blood and Gold with a clinical finish from Openda’s pass.
This dramatic turn of events left Auxerre staring relegation in the face, sitting inside the bottom four and a point adrift of Nantes. Undeterred, Han-Noah Massengo looked to take matters into his own hands with a surging run towards goal, only to fire his resulting shot narrowly wide.
It could have got worse for Auxerre before the break had Radu not denied Fulgini again in a swift Lens break forward.
For all of Radu’s fine work in keeping Auxerre in the contest, a horribly mistimed challenge allowed Claude-Maurice to take advantage and slot the ball into an empty net just three minutes into the second half.
The hosts were on the ropes, and Openda was inches away from rubbing salt into their gaping wounds after narrowly failing to connect with Machado’s enticing ball across the box.
However, there was hope of a comeback out of nowhere when a goalkeeping disaster from Lens’ Jean-Louis Leca allowed M'Baye Niang to halve the deficit.
Machado thought he had restored the visitors’ two-goal advantage after heading from Florian Sotoca’s delivery, but this was chalked off with the latter in an offside position.
In a minute which best summed up Auxerre’s season, Toure inexplicably headed wide with the goal gaping from Gideon Mensah’s cross, before Lens extended their lead. Another horrendous Radu error allowed Openda’s effort to squirm through his grasp and relegation beckoned for the hapless hosts.
While the inquest will begin into a torrid campaign for Pelissier’s side, Franck Haise can reflect on a superb season for Lens and the prospect of UEFA Champions League football next season after a seventh consecutive Ligue 1 victory.
In doing so, La Maison Jaune ended a dismal run of 14 matches without a victory, leapfrogging Auxerre to condemn them to Ligue 2 football next season.
Heading into the final day of a dismal Ligue 1 campaign two points adrift of safety, the equation was relatively straightforward for Nantes - win, and hope Auxerre could not do so against second-placed Lens.
The alternative was certain relegation, but the home fans were in full voice, and their side mirrored that defiant attitude with an assertive start, taking the lead in the 16th minute.
Ludovic Blas skillfully shrugged off a couple of Angers challenges, forcing his way into the box before picking out Ignatius Ganago, who adjusted his feet to blast in from close range.
That early goal lifted La Maison Jaune out of the relegation zone, and news of an all-important Lens goal soon filtered through to further strengthen Nantes’ footing. The game’s tempo dropped somewhat after an electric start from the hosts, but Nantes remained firmly on top, albeit without really troubling Yahia Fofana further.
However, Pierre Aristouy was offered a timely reminder of his side’s delicate position on the stroke of half-time, when Nabil Bentaleb’s mesmeric run ended with Abdallah Sima finding the back of the net, only for the offside flag to thwart him.
Unsatisfied with a slender one-goal lead, Nantes flew out of the blocks after the break, and thought they had a chance to double their lead from the spot. Ganago twisted his way into the area before going to ground, but while Blas held the ball in anticipation, Clement Turpin jogged over to the pitchside monitor before retracting the penalty award.
A second goal for Lens against Auxerre was the perfect antidote for Nantes’ disappointment, but with 15 minutes to go, the hosts had done little to extend their lead and Angers had seemingly played their way into the contest.
Auxerre also pulled one back, putting the closing minutes of this Ligue 1 relegation dogfight on a knife edge. Yet Nantes dug their heels in for the remainder of the game, doing just about enough to see out a pivotal win that confirms an 11th consecutive season in France’s top flight.
Defeat for Angers is purely academic with the bottom side’s fate long since decided, though a comparatively strong end to the campaign under manager Alexandre Dujeux gives Le SCO something to build on as they aim for a swift return to Ligue 1.