Jake McIntrye amassed 22 points as Clermont Auvergne defeated Top 14 strugglers Stade Francais, as Bordeaux-Begles drew with Montpellier.
The top two in the Top 14 claimed huge victories to stay unbeaten as both the defending champions and last year's runners-up were beaten.
The top two in the Top 14 both triumphed on Saturday, with Bordeaux-Begles and Lyon improving to three wins from three this season.
The second round of Top 14 fixtures saw hard-fought wins for Clermont Auvergne, La Rochelle and Montpellier, among others, on Saturday.
There were shock wins for Bayonne and Bordeaux-Begles as the Top 14 returned for the 2019-20 season on Saturday.
There will be a new Top 14 champion after Castres missed out on a top-six finish with a final-day defeat to Toulon.
Neither Bordeaux Begles nor Stade Francais can make the play-offs in the Top 14 after suffering painful defeats in the penultimate round.
It promises to be an enthralling climax to the battle for Top 14 play-off spots after Stade Francais claimed a derby win over Racing...
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Greig Laidlaw's boot and a pair of tries from Apisai Naqalevu helped Clermont Auvergne battle back to beat Stade Francais on the road.
La Rochelle put Pau to the sword and Castres also enhanced their chances of reaching the play-offs with a win in Bordeaux.
Toulon may have been at a numerical disadvantage for most of the second half but they still managed to defeat Top 14 leaders Toulouse.
Toulouse are now unbeaten in 14 Top 14 matches after grinding it out at La Rochelle, while Racing 92 got the better of Bordeaux.
There were big wins for 2017-18 Top 14 finalists Castres and Montpellier on Saturday, with Benjamin Urdapilleta inspiring.
Toulouse's lead in the Top 14 table is down to a solitary point after Clermont Auvergne thrashed Grenoble. Lyon, meanwhile, lost at home.
Zack Holmes scored 15 points as Toulouse extended their lead at the Top 14 summit, while Stade Francais boosted their play-off hopes.
Perpignan finally had a win to celebrate, while Clermont Auvergne were too good for Bordeaux-Begles in Top14.