Clermont edged Perpignan 29-23 on Saturday to rack up their 40th successive win at their Marcel Michelin stadium fortress and move a point behind Toulouse in the French Top 14.
Toulouse were surprisingly defeated by Bordeaux on Friday and Clermont took their opportunity despite a bruising start that saw prop Lionel Faure and Perpignan hooker Charles Geli both yellow-carded for a second-minute punch-up.
Number eight Alexandre Lapandry scored Clermont's only try of the game in the ninth minute, with David Skrela kicking eight penalties.
Perpignan had the consolation of out-scoring Clermont thanks to first-half efforts from Joffrey Michel and Cavalieri Plante.
Welsh star James Hook converted both tries and booted three penalties.
"I am satisfied, especially by our tactics," said Clermont coach Vern Cotter.
"It was important to have that sort of commitment ahead of our European Cup quarter-final tie."
Stade Francais moved into the play-off places with a 53-27 bonus-point mauling of Agen, running in seven tries in the process.
Argentine star Felipe Contepomi grabbed a brace, with Italian national skipper Sergio Parisse, Australian forward David Lyons, Aussie centre Morgan Turinui, French winger Julian Arias and Kiwi forward Aled de Malmanche also scoring.
The win put Stade onto 52 points, the same as fifth-placed Montpellier and three ahead of Racing Metro, who play at Toulon later on Saturday.
Fourth-placed Castres defeated Montpellier 27-18 to maintain their chances of featuring in the six-team play-offs.