Bordeaux were looking to bounce back from a shock defeat to Lille a fortnight ago but were stunned by Samassa's seventh-minute strike and found Valenciennes goalkeeper Guy N'dy Assembe in inspired form.

Lyon spurned the chance to move top after being held to a surprise draw at bottom side Grenoble.

Cesar Delgado put Lyon in front after 66 minutes and Grenoble's Laurent Courtois was sent off soon after, but Danijel Ljuboja equalised just 60 seconds later.

And it was Auxerre who took advantage of Bordeaux's defeat to move top with a 2-0 victory over Monaco in the day's late game.

Adama Coulibaly scored on the stroke of half-time and Delvin Ndinga ensured it was seven wins in succession with the second in the closing minutes.

Lens came from behind to secure only their fourth Ligue 1 victory of the season with a 2-1 win over Nancy.

Paul Alo'o Efoulou broke the deadlock eight minutes into the second half but Issam Jemaa levelled nine minutes from time and Kevin Monnet-Paquet notched the winner three minutes later to complete a stunning comeback.

A goal from Asamoah Gyan 10 minutes from time condemned Le Mans to their seventh successive away defeat as Rennes won 2-1.

Kader Mangane gave Rennes an early lead before Rolland Lamah levelled for the visitors, but Gyan's late decider means Le Mans are still searching for their first away point this season.