Reigning Top 14 champions Toulouse squeezed past lowly Vannes 29-23 on Saturday, while seven-try Lyon took top spot with an emphatic win against Pau.
Despite France captain Antoine Dupont starting on the bench, Toulouse still had plenty of star names in their XV, including Romain Ntamack, Teddy Thomas and Blair Kinghorn.
But Toulouse were nonetheless pushed all the way by a Vannes team who remain pointless at the bottom of the Top 14 table.
Tries by Dupont's replacement at scrum-half Paul Graou, Santiago Chocobares, Thomas and Kinghorn, as well as nine points courtesy of the boot of Ntamack sent Ugo Mola's men up to second in the table.
Eric Marks and Ben Stevenson crossed the whitewash for the hosts, with Anthony Bouthier slotting home a drop-goal and fly-half Maxime Lafage converting both tries and kicking a further two penalties.
One point separated the teams at halftime and the gap remained the same heading into the final 10 minutes until Scottish full-back Kinghorn jotted down to seal the victory for Toulouse.
'COMPOSURE'
Lyon defeated Pau 51-25 in a clash of the previous top two to rise to the summit.
Lyon dotted down seven tries at the Stade de Gerland to extend their perfect start to three wins in as many games.
After a dominant display at Racing 92, Karim Ghezal's men inflicted a first defeat this season on visitors Pau.
The two teams traded tries for much of the game but Lyon pulled ahead after Pau's Baptiste Pesenti was shown a red card for a dangerous tackle on Mickael Guillard after 51 minutes.
Pau scored four tries themselves, with Portuguese centre Rodrigo Marta touching down twice in a three-minute spell around the quarter-of-an-hour mark.
But Lyon stalwarts Jiuta Wainiqolo, Guillard and scrum-half Baptiste Couilloud all scored, with Adrien Seguret's late try securing a bonus point.
"We aren't looking at the standings," said Lyon captain Antoine Deliance.
"Last year we were top of the table after three rounds with three wins. The challenge is to handle difficult spells better throughout the season."
Last season's runners-up Montpellier notched their first home win of the season, 50-13 against Perpignan, as Bayonne blew hot and cold before seeing off Clermont 46-24.
Racing 92 bounced back after two dismal performances with a spirited 20-10 comeback win at La Rochelle.
The capital club were 10-0 down at the interval but turned the tide, sparked by a magnificent break by Max Spring to score a 52nd-minute try.
The visitors took the lead six minutes from the end, with Romain Taofifenua securing victory with their second try in the final minute.
Toulon fell 29-27 on the road against Castres, their third straight defeat.
Argentine flyhalf Tomas Albornoz failed to convert what would have been a winning drop goal for Toulon after the final hooter.