With top two La Rochelle and Montpellier not in action until Monday (AEDT), Clermont had to work hard to capitalise on its chance to leapfrog the pair.

Castres held a 13-11 lead at the break at Stade Marcel Michelin, but Clermont dominated the second period, with early tries from Judicael Cancoriet and Noa Nakaitaci putting daylight between the teams.

Toulouse was comfortable 31-3 victor over Grenoble to maintain its promising recent form, laying down the foundations for victory by going in 17-3 up at half-time.

The result sees Toulouse go fourth, while Grenoble remains rooted to the bottom of the table with just one win from seven matches.

Bayonne, which had been level on points with Grenoble heading into the weekend's action, picked up two points in a 22-22 draw with Lyon - Raphael Lagarde kicking three points from the tee with two minutes left to secure a share of the spoils.

Bordeaux-Begles and Brive keep pace with Toulouse after victories over Pau and Racing 92 respectively.

The former turned around a 28-20 deficit with 10 minutes remaining to triumph 30-28 at Stade du Hameau, while Brive was 25-16 winner against Racing.