Clermont stay top after 69th successive home win
Clermont's scrum-half Thierry Lacrampe scores a try during a French Top 14 Rugby Union match against Biarritz Olympique on December 21, 2013 at the Marcel Michelin stadium in Clermont-Ferrand, central France
As they had done in their recent back-to-back European Cup wins over Llanelli Scarlets, it took until the second half for Clermont to find top gear after they only led 6-3 at half-time courtesy of two penalties from Mike Delany.
But once Thierry Lacrampe, Brock James and Wesley Fofana had been summoned from the bench, Clermont pulled away with Julien Malzieu, Regan King, Gerhard Vosloo and Lacrampe all scoring tries.
Biarritz were the last team to triumph at Clermont's Marcel-Michelin stadium four years ago, but they never looked remotely like adding to that record on Saturday and they remain nine points adrift of second-bottom Bayonne.
"We could have taken our foot off the gas after our European campaign, but we responded well," said Clermont coach Vern Cotter.
"With each game, we are playing at a higher level which is important."
Castres are second after a 37-13 win over 2009 champions Perpignan who have now lost six games on the bounce.
The defending champions also collected a bonus point after tries from South African flanker Antonie Claassen, who crossed for a brace in the 13th and 17th minutes, fly-half Remi Tales and Fiji centre Seremaia Bai.
European champions Toulon had gone top briefly earlier in the day after thrashing Montpellier 43-10, inflicting a fifth successive defeat on Fabien Galthie's out of form side.
Jonny Wilkinson gave the hosts the lead in the ninth minute with a crisply-taken penalty but the animosity between the two sides threatened to boil over when Toulon's Springbok lock Bakkies Botha -- who had blown a kiss at Montpellier fly-half Francois Trinh-Duc prior to the penalty -- came to blows with Mamuka Gorgodze, who is set to play for Toulon next term.
The two sides got back to playing rugby and Trinh-Duc levelled the scores in the 16th minute with a penalty but Wilkinson restored Toulon's lead a couple of minutes later when Montpellier strayed offside and added another in the 23rd.
Montpellier's indiscipline ruined their hopes of winning the match as they messed up their few forays into Toulon territory with petty infringements.
Wilkinson had to go off temporarily after suffering a nose injury -- which required two stitches -- when being accidentally trod on by Robert Ebersohn.
However, in his absence Toulon scored a try through Juan Smith who went in in the left hand corner in the 33rd minute after good work by scrum-half Sebastien Tillous Borde -- former Wallaby fly-half Matt Giteau added the extra points for 16-3.
Montpellier were torn apart again four minutes from the break with David Smith and Giteau involved and only prevented from scoring a try by Jim Hamilton's deliberate offside which finally broke the referee's patience and he sin-binned the Scottish international -- Giteau converted the penalty for 19-3.
Toulon took full advantage of Hamilton's absence as they extended their lead shortly after the restart as Smith went over and they added a third when hooker Jean-Charles Orioli touched down in the 47th minute.
Giteau converted for 31-3 and the Toulon fans performed their traditional showering of newspapers when their side gets a bonus point.
Montpellier at last conjured up something constructive and Gorgodze bustled over the line to score a try which was converted for 31-10 -- but minutes later former Wallaby Drew Mitchell scored his first try in the Top 14 as he intercepted a Trinh-Duc pass and ran it back.
Giteau converted for 38-10 and despite Montpellier once again being reduced to 14 men when replacement centre Wynand Oliver was sin-binned Toulon were unable to add to their total until three minutes from time when No8 Steffon Armitage -- who looks set for a long run as Chris Masoe is out for rest of the season -- finished off a flowing move in the left hand corner.
On Friday, fourth-placed Stade Francais dished out a 21-6 defeat to Grenoble.