Rennes were grateful to goalkeeper Benoit Costil after he saved a late penalty minutes before Jonathan Pitroipa wrapped up a 3-1 victory at Nancy with a goal five minutes from time.
Victory guides Rennes to fifth in Ligue 1 with their hosts remaining rooted to the bottom with just five points.
It was Nancy, though, who came within inches of opening the scoring after quarter of an hour when only the outstretched leg of John Boye prevented Yohan Mollo from converting Massadio Haidara's whipped cross from the left wing.
Rennes then took the lead. Chris Mavinga found space on the left and bent a teasing cross to the far post which found Mevlut Erding, who had lost his marker before heading beyond goalkeeper Guy N'dy Assembe.
Erding continued to cause problems for Nancy with two efforts in the space of a minute blocked by the home defence but there was still just one goal between the sides at the break.
Nancy duly equalised six minutes into the second half. Simon Zenke turned Jean-Armel Kana-Biyik inside out before slamming a right-footed shot into the top left corner of the goal.
Romain Alessandrini dragged a shot narrowly wide for Rennes minutes before his team-mate Pitroipa cleared off the line from Thomas Ayasse's header.
However, it was the visitors who scored next with an absolutely stunning goal from Alessandrini after 74 minutes.
Kevin Theophile-Catherine's free-kick was helped on by Erding towards Alessandrini who slammed a first time left-footed volley into the top left corner of the goal.
With nine minutes left, Nancy were awarded a penalty when Boye brought down Zenke.
Paul Alo'o Efoulou sent a right-footed shot towards the bottom right corner but Costil got down and made a superb save.
And Rennes took full advantage with five minutes left when Pitroipa profited from a Massadio Haidara misjudgement to poke the ball over N'dy Assembe before nodding the ball into an empty net.