Grzegorz Krychowiak's first-half penalty helped Reims guarantee their Ligue 1 status next year after a battling victory over Lorient.
Reims were promoted from Ligue 2 last year and were still in slight danger of a return as they lay four points clear of 18th-placed Nancy with two matches remaining.
But tonight's victory, secured when Krychowiak netted from the spot just after the half hour, pushed Hubert Fournier's men five points clear of the drop ahead of the final weekend of the season.
They started like a team fighting for survival, with Lorient goalkeeper Fabien Audard having to make a fantastic save in the opening minutes from Gaetan Courtet's back post header.
Audard also had to be at his best when Diego - who was the one to set up Courtet - again caused a nuisance to the visitors by teeing up Nicolas de Preville, whose looping header was tipped over.
Courtet perhaps should have done better once more when he found himself unmarked in the area but could only direct his shot straight at Audard.
The Lorient custodian was not rewarded for his excellent saves as Senegal defender Lamine Gassama pushed Diego inside the area to give Reims a penalty, with Krychowiak sending Audard the wrong way.
The only downside of a commanding first-half performance from Reims came when Diego left the pitch just before half-time after appearing to twist his knee.
Their dominance continued after the interval, though, with Aissa Mandi's cross finding Courtet, whose diving header went inches wide.
Audard kept the deficit to just one goal with another magnificent full stretch save from Floyd Ayite's low right-foot volley from the edge of the area.
It could have proved a key moment as the away side came on strong in the closing stages although Benjamin Corgnet's cross-cum-shot - which only just missed the target - was the closest they had come to a goal in 74 minutes.
And Reims goalkeeper Kossi Agassa was forced into his first meaningful action of the night as he palmed away Kevin Monnet-Paquet's fierce drive to ensure the hosts walked away with the spoils.