Front-runners Lyon and Bordeaux-Begles made it four wins from four in the Top 14 on Saturday while champions Toulouse slipped to their third defeat in four matches.
Full-back Toby Arnold scored three of Lyon's nine tries as they crushed Brive 59-3 while Bordeaux also ran riot with seven tries in their 52-3 thrashing of Stade Francais.
Lyon and Bordeaux top the table with 18 points. They are due to meet in round six on October 5.
Toulouse, meanwhile, lost 28-13 at La Rochelle and Clermont slipped to their second successive defeat 37-28 to Pau.
Brandon Fajardo kicked four penalties to help newly-promoted Bayonne to a 27-17 win over Castres.
Lyon, playing their third home match and profiting from the fact they are missing just one player, Fiji's Josua Tuisova, to World Cup duty, were in blistering form against Brive.
Arnold scored a first-half hat-trick as Lyon opened up a 31-3 lead.
Another four tries followed in the second half as they took their second bonus point win of the season.
"The players put things in order, they showed maturity," said Lyon head coach Pierre Mignoni.
"There was waste but it is satisfactory overall. But we have only won four games and there are twenty-two left."
They have now scored 19 tries and have still yet to concede one.
Bordeaux were equally ruthless against a Stade Francais side that had won just once this season.
Santiago Cordero crashed over in the second minute and there were further first half tries from Maxime Lucu and Lasha Tabidze.
Bordeaux led 24-3 at the interval and continued to pile on the pressure in the second half with four further tries to close out a second bonus-point win of the season.
- Toulouse struggle -
Toulouse, significantly weakened by World Cup call-ups, were playing their third match on the road having already lost 30-25 to Bordeaux in the opening round and 22-12 at Lyon.
Their only win of the season came last weekend at home when they edged Racing92 20-17.
La Rochelle had also lost their two away matches but managed to make home advantage count.
Leading 9-6 at the break, La Rochelle took a grip on the game just after the restart with tries from flanker Wiaan Liebenberg and wing Arthur Retiere.
"We were nowhere to be seen on the restart and in five minutes gave away two tries," said Toulouse coach Ugo Mola. "We made schoolboy errors."
Toulouse had left wing Werner Kok sent off in the 54th minute and went further behind when full-back Vincent Rattez scored La Rochelle's third try.
Toulouse denied the home side a bonus point, however, when Joe Tekori went over 12 minutes from time.
Clermont welcomed back Morgan Parra for his first game since May 10 but the scrum-half, spurned by France coach Jacques Brunel for the World Cup, could not stop Pau from claiming their first win in Auvergne for 17 years.
Giovanni Habel-Kuffner gave Pau the opening try after just four minutes and the visitors led 17-11 at the break. The sides traded tries in the second half but it was Pau who held on to go third in the standings.
Newly-promoted Bayonne climbed up to fifth with their win over Castres.
Four penalties from Fajardo and a try from Aymeric Luc put them 17-3 up at the break and, although the 2018 champions came back strongly in the second half, the Basques held out for the win.