Ligue 1: Nancy 1 Stade Rennes 3
Mevlut Erdinc put the visitors in front after 21 minutes, though parity was restored when Nigerian forward Simon Zenke found the net in the 50th minute.
Nancy fought gallantly in search of the lead, but came undone when Romain Alessandrini handed Rennes the advantage on 74 minutes.
Burkina Faso international Jonathan Pitroipa put the result beyond doubt with six minutes to go, leaving Nancy deep in the relegation zone with just five points from 12 matches.
Rennes are fifth on the table with 19 points, but could slip as low as ninth depending on other results at the weekend.
Nancy travel to face 19th-placed Troyes next week, while Rennes will take on Paris Saint-Germain in the French capital.