Troyes took their fight for Ligue 1 safety to the final weekend after exacting revenge on 10-man Bordeaux for their Coupe de France defeat in midweek.
Fabien Camus slid in the only goal after 56 minutes as he timed his run from the left to meet Jeremie Brechet's through ball.
Bordeaux won their Coupe de France semi-final 2-1 on Tuesday but any chance of breaking Troyes hearts again were prevented when Julien Faubert harshly saw red after 65 minutes.
Troyes will therefore head into their final-round clash at Valenciennes three points adrift of a trio of clubs.
Sochaux appear the most vulnerable of those sides, with their goal difference just a single goal better, and a trip to Bastia on the final day.
Camus set up Troyes first opening on 15 minutes for Jean-Christophe Bahebeck who unleashed a 30-yard drive that had Cedric Carrasso scrambling.
Bahebeck then headed inches wide from a Stephane Darbion corner before Bordeaux tried to hit back.
Gregory Sertic's 38th-minute free-kick flew narrowly over before Troyes goalkeeper Yohann Thuram-Ulien kept out a close-range Cheick Diabate effort in the shadows of half-time.
Troyes claimed the crucial goal 11 minutes into the second half after the pitch opened up for Brechet.
The midfielder surged into the space in front of the away defence and waited for Camus to make his run from the left. A perfectly-weighted pass meant Camus hardly needed to break stride before he picked his spot past an exposed Carrasso.
Troyes night then got even better after 65 minutes when Faubert saw red after what appeared an unintentional tangle of legs with Bahebeck. The once-capped France defender was the last man, however, and once the referee decided he initiated the collision he had to go.
Troyes missed the chance to improve their goal difference thereafter as Carrasso denied Bahebeck and and Camus in the closing stages.