Racing 92 ended a difficult week on a high note as a last-minute try from Camille Chat secured a dramatic 29-22 victory over Parisian rival Stade Francais.

Putting aside the allegations of doping made against several of its high-profile players in the build-up to the derby clash, Laurent Labit's men produced an impressive performance to secure their fourth win of the season.

Juan Imhoff, one of the players who was reported to have failed a drugs test after June's Top 14 final, scored Racing's opening try, before Jules Plisson looked to have snatched a share of the spoils for Stade when he landed a 77th-minute penalty to make it 22-22.

Hooker Chat, however, duly powered over from close range to clinch it for the host.

La Rochelle, meanwhile, climbed to the top of the table despite conceding a last-gasp penalty in a 17-17 draw with Toulon.

Four penalties from Brock James and a Steeve Barry try had looked set to secure a fifth win of the campaign for Patrice Collazo's men, but Pierre Bernard held his nerve to secure the visitors a share of the spoils. 

Bordeaux-Begles built upon its win over Pau last weekend by edging out Brive 27-25, with Blair Connor and Adam Ashley-Cooper both finding the line and Lionel Beauxis adding a further 17 points with the boot.

Former Harlequins fly-half Ben Botica kicked 20 of Montpellier's points as it consolidated its position among the leading pack with a 28-20 victory against Castres at the Altrad Stadium. 

Grenoble climbed off the foot of the table as Steven Setephano, Nigel Hunt, Sona Taumalolo, Alexandre Dardet and Maritino Nemani all grabbed tries in a resounding 44-16 win over fellow struggler Bayonne. 

Clermont-Auvergne can reclaim spot with victory over Toulouse on Monday (AEDT).