Montpellier Herault capped off a miserable week for Clermont Auvergne with a 19-15 victory at the table-toppers' Stade Marcel Michelin.
Clermont, who were dumped out of Europe by Bordeaux Begles last week, were on the back foot early on thanks to Francois Trinh-Duc's 12th-minute drop goal. It proved to be the only score until just after the half-hour mark when Camille Lopez's penalty levelled matters.
But the visitors hit back immediately with a Marvin O'Connor try, converted by Benoit Paillaugue, who then added two quick-fire penalties to send Montpellier in 16-3 up at the break.
Another Lopez penalty and two from Brock James closed the gap to three points with 15 minutes to play, but Demetri Catrakilis fired a second Montpellier drop goal to extend the lead back to six.
James added another penalty on 70 minutes, but it was to be the final score of the game.
Dan Carter once again played an influential role as Racing 92 eased to a 26-3 victory over Oyonnax to move four points clear of Clermont.
Carter, Henry Chavancy, Juan Imhoff and Yannick Nyanga Kabasele all went over for the hosts, three of which were converted by the legendary All Black, while Nicky Robinson's 22nd-minute penalty was the only score for Oyonnax.
After last week's European heroics, Bordeaux came crashing back to earth with a 19-9 defeat at Castres Olympique.
Four penalties from Ben Urdapulleta saw the hosts race into a 12-0 lead, but two in reply from Simon Hickey either side of half time and another from Pierre Barnard saw the Begles within three.
But Johnnie Beattie's try on 73 minutes, converted by Urdapulleta, was enough for Castres to leapfrog their opponents in the Top 14 table.
Grenoble held off two comebacks from rock-bottom Agen in a thrilling 33-27 win at the Stade Armandie.
Converted tries from Chris Farrell and Arnaud Heguy, plus three Jonathan Wisniewski penalties, gave the visitors a 23-8 lead at the end of a first half that saw Agen's Remy Vaquin and Grenoble's Sona Taumalolo both sent off just after the half hour mark.
But Agen closed the gap to six points thanks to Johann Sadie's try and a trio of penalties from Burton Francis, before Grenoble peeled away again when Nigel Hunt went over. Another Francis penalty wasn't enough as Grenoble held on for the points.
High-flying Stade Toulousain thrashed lowly Pau 54-3. Sebastien Bezy and Maxime Medard ran over two tries each, while Gael Fickou, Paul Perez, Gregory Lamboly and Vincent Clerc also touched down. Colin Slade's fifth minute penalty was the visitors' only score.
In Friday night's match, Brive full-back Gaeten Germain kicked seven penalties and converted Karlen Asieshvili's last-minute try as they beat La Rochelle 28-6, , while on Sunday, Toulon closed the gap on the lead leaders with a 23-16 win over Stade Francais. Bryan Habana opened the scoring in the 11th minute, while Eric Escande kicked six penalties. Morne Steyn, with a try that he converted himself and three penalties, scored all the visitors' points.
Press Association Sport contributed to this report.