Castres extended their winning streak to seven games after beating Montpellier 21-16 to draw level at the Top 14 league table.
South African Rory Kockott kicked seven penalties to down last season's beaten finalists at a buoyant Stade Yves du Manoir.
It was the fourth match in succession that Castres have failed to score a try but the boot of Kockott was enough to see them draw alongside league leaders Clermont, who occupy top spot by virtue of their superior points difference.
Elsewhere, Biarritz remain rooted to the bottom of the table after a 15-15 draw at home with their nearest rivals Lyon. The visitors led for most of the match until Argentina World Cup star Manuel Carizza crossed the line on 61 minutes to ensure the points were shared.
Agen blitzed Stade Francais 37-13 to move into the top six while third-placed Toulouse registered their sixth win of the season with a 56-6 thumping of sorry Bordeaux-Bègles.
Toulon, in fourth, beat Racing Metro 16-9 and Brive saw off Bayonne 30-10 to round of the day's action.