Top 14 leaders Montpellier suffered a humbling defeat as they were beaten 26-0 by Racing 92 on Sunday in the Parisian side's final game at the Stade Olympique Yves-du-Manoir.
Montpellier had won their last three games, but were put to the sword by the hosts, who ran in three tries and saw 11 points come from the boot of fly-half Pat Lambie to give their home stadium in Colombes a fine send-off before they move to the newly built U Arena.
Racing, who are set to lose Dan Carter at the end of the season after he announced this week that he is to leave for Japan's Kobelco Steelers, went ahead courtesy of the first of three Lambie penalties 23 minutes in.
And seven minutes later Albert Vulivuli crossed for the game's opening try.
Another Lambie three-pointer made it 13-0 at the break and Brice Dulin extended the lead further when he went over out wide.
Juan Imhoff added the finishing touches with a 70-metre solo effort from an interception as Racing recorded a bonus-point success that marked their fourth successive win.
-- Racing 92 (@racing92) November 26, 2017
Lyon could have gone top had they taken advantage of Montpellier's slip-up, but they too stumbled at home against Toulouse.
Lionel Beauxis' penalty put Lyon ahead after 13 minutes but a Toulouse penalty try and a Zack Holmes converted try put the visitors into a 14-3 lead.
A late hit from Dorian Aldegheri saw him sent to the sin bin and Beauxis took advantage with two penalties to narrow the gap, only for a late Thomas Ramos penalty to put the game beyond doubt.
Lyon remain four points behind Montpellier in third, level on points with Racing, while Toulouse are a point further back.