Castres held on for a 22-16 win over Toulouse in a bone-crunching Top 14 battle at the Stade de la Méditérranée in Béziers on Saturday.
Despite a strong comeback from the European champions, Castres led from start to finish in an error-riddled encounter characterised by a mammoth combat between the respective packs.
Castres raced to a 13-0 lead thanks largely to Kiwi duo Cameron McIntyre and Chris Masoë.
An early drop goal from fly-half McIntyre got the ball rolling after just three minutes.
The game's first try came from number eight Masoë, who used his power to barge over after McIntyre had bust through the Toulouse defence and timed his off-load to perfection. Masoë dropped the ball in the act of diving over but referee Christophe Berdos failed to ask the TMO to have a look, much to the Toulousains' disgust.
Full-back Romain Teulet added the conversion and a penalty to give the host a healthy advantage 13-3 at half time which was a fair reflection of their territorial advantage.
After the break, young Toulouse fly-half Jean-Marc Doussain added two more penalties to his first-half effort to reduce the gap but Teulet replied in kind to restore the hosts' ten-point lead going into the final quarter.
Teulet looked to have sealed the game for Castres with his fourth penalty but Toulouse bounced back when Vilimoni Delasau broke down the touchline, the cavalry arrived and pushed replacement lock Sylvain Nicolas over to leave the scores at 22-16 with ten minutes left.
It was all Toulouse in the closing stages, but the seventeen-time French champs were unable to break down the courageous Castres defence and will have to settle for a losing bonus point.
Pens: Teulet 4
Pens: Doussain 3
Castres 15 Romain Teulet, 14 Romain Martial, 13 Romain Cabannes, 12 Seremaia Baï, 11 Yoan Audrin, 10 Cameron McIntyre, 9 Alexandre Albouy (c), 8 Chris Masoë, 7 Yannick Caballero, 6 Ibrahim Diarra, 5 Matthias Rolland, 4 Rodrigo Capo Ortega, 3 Luc Ducalcon, 2 Mathieu Bonello, 1 Yannick Forestier.
:Remplacements : 16 Benjamin Kayser 17 Kirill Koulemine 18 Jannie Bonrman 19 Pierre-Emmanuel Garcia 20 Florian Denos 21 Sebastien Tillous-Borde 22 Michael Coetzee
Toulouse: 15 Maxime Médard, 14 Vincent Clerc, 13 Yann David, 12 Florian Fritz, 11 Cedric Heymans, 10 Jean-Marc Doussain, 9 Nicolas Vergallo, 8 Shaun Sowerby, 7 Theirry Dusautoir (c), 6 Gregory Lamboley, 5 Romain Millo-Chluski, 4 Yoann Maestri, 3 Census Johnston, 2 William Servat, 1 jean-Baptiste Poux.
:Remplacements : 16 Virgil Lacombe, 17 Benoit Lecouls, 18 Sylvain Nicolas, 19 Jean Bouilhou , 20 Remi Lamerat, 21 Nicolas Bezy, 22 Vilimoni Delasau, 23 Daan Human.