Rennes managed their second away win of the season as they all but consigned Caen to relegation.
A second half header by Giovanni Sio was the difference between the two teams in the all to play for tie for the hosts.
By full time, a deathly silence surrounded the Stade Michel d'Ornano with SMC only a point from third bottom with one week to play.
However, but for some late heroics from Caen-native and departing Rennes goalkeeper Benoit Costil, the night could have been better for SMC.
Rennes don't take advantage of domination
The first chance of the match came after nine minutes when Rennes forward Firmin Mubele struck the frame of Rémy Vercoutre one-on-one.
Midway through the half, Yoann Gourcuff could have got the opener for the Bretons when his low-range drive from inside the box was strongly stopped by Vercourtre.
Five minutes before the interval, Gourcuff passed up an even better opportunity when he was unable to guide a header goalwards from the penalty spot.
Costil wins all three points for Rennes
The second half took its time to produce noteworthy action which resulted in the Caen change of Ronny Rodelin on for Jean-Victor Makengo.
The sub almost made an immediate impact when Rodelin's six-yard header miraculously avoided the target.
Rodelin once again should have broken the deadlock on 65 minutes when his header smacked the crossbar.
At the other end, Rennes were denied an opener thanks to the quick reflexes of Vercoutre who used his frame to stop Benjamin André from scoring from three yards.
Unfortunately for Vercoutre, there was nothing he could do to stop Sio from scoring the first goal as his looping header nestled into the top-right corner.
The Ivorian seemed to be in the air an eternity as he used his man as leverage to head into the net to score his ninth of the season.
In the last minute of added time, Costil was made to work to deny Caen a late equaliser as he managed to parry out shots from Jonathan Delaplace and Frédéric Guilbert in quick succession.
What is assumed to be Costil's last appearance for Rennes will be next Saturday's tie to champions to be Monaco at Roazhon Park, while Caen will be biting their nails against PSG to avoid relegation.