Sunzu’s diving header in the 84th minute off a midfielder Sebastian Roudet’s free kick handed Sochaux the precious three points in their battle to survive demotion.
The goal was the Zambia defenders second for Sochaux after scoring in another 1-0 win home win over Nantes on February 1.
Sunzu has now scored two goals in seven successive Ligue 1 appearances since joining second from bottom Sochaux on January 3 from DR Congo club TP Mazembe on a Euro 1 million deal.
The defender including his compatriot and midfielder Nathan Sinkala played the full 90 minutes while striker Emmanuel Mayuka was side-lined for Saturday’s game due to injury.
Meanwhile, Sochaux remain second from bottom with 18 points after 25 games played with another 13 left before their fate is known.