Bordeaux-Begles hammer Toulouse in Dupont absence
Scrum-half Maxime Lucu scored 17 points for the home side, who moved up to fourth in the table, two points off second-placed Montpellier in the final automatic semi-final berth.
Toulouse remain top of the table despite their first league loss since January and are 10 points clear before hosting Montpellier next weekend with Dupont expected to return.
The game was billed as the battle between France's two leading fly-halves as Matthieu Jalibert welcomed rival Romain Ntamack to the Stade Atlantique.