Sireli Bobo piled more misery on Castres as La Rochelle cruised home 41-16 to move out of the bottom two at the expense of their visitors.
The promoted side are yet to pick up a point on the road, but on home soil they had already beaten Toulouse, and this win was even more convincing.
For Castres, it means they have now lost four of their first five games, and the tension clearly got to them in the second half as they lost their discipline, both defensively and in general.
La Rochelle took full advantage scoring four tries through Jean-Pascal Barraque, Bobo twice and Kini Murimurivalu, to secure a bonus-point success.
Castres opened the scoring with an early penalty after La Rochelle struggled to deal with a rolling maul. Rory Kockott made no mistake from 35 metres out.
The home side responded immediately though centre Barraque after a great team move.
La Rochelle initially went right off the back of a scrum on halfway, before coming back left. Peter Grant then chipped into space and a fortunate bounce allowed Bobo to collect the ball. The veteran Fijian winger then fed Barraque on his shoulder for a simple run-in. Audy added the extras to make it 7-3
Castres had struggled early this season in the scrum, but they seemed to have improved on this occasion, and when they got the upper hand midway through the half, they were able to cut the deficit back to a single point with another Kockott penalty.
La Rochelle responded with a penalty of their own from Audy when Kockott’s clearing kick put all his teammates offside, and the home scrum-half added another two minutes later to extend the lead to 13-6.
Castres’ rolling maul had not really been working, but they used it to put the pressure on the home side soon after, and a marginal call allowed them to add another three points.
However as had been the case for much of the half, the visitors switched off as soon as they had scored, and they gave Audy another penalty opportunity, which Audy gratefully accepted to make it 16-9.
Castres still looked to be some way off their best, but they were given a boost when La Rochelle lost their skipper Uini Atonio for ten minutes after he caught Didier Combezou with a high tackle.
Even that wasn’t enough for the visitors though, and they quickly levelled up the numbers with a yellow card of their own, Rodrigo Capo Ortega harshly sin-binned for pushing in the lineout. Audy continued his perfect start to the evening to make it 19-9 at the break.
The visitors needed to score first in the second half, but instead it was La Rochelle who stretched their lead thanks to Bobo.
After a huge scrum, the visitors progressed to the Castres 22, and when Kockott drifted early around the fringes, Bobo scooped the ball up and sprinted over. Audy’s simple conversion made it 26-9.
With a 17-point lead La Rochelle were able to start dreaming of a bonus-point win, but Castres dampened the mood with an immediate response through Combezou.
The visitors turned the ball over in the La Rochelle 22, and with the home defence scrambling, Castres spread the ball wide, and Combezou had more than enough space to dive over. Kockott converted from out wide to reduce the deficit further.
Atonio’s return gave the home side an extra man, and they were able to add another three points when Yannick Caballero was caught with his hands in a ruck soon after.
And it almost got worse for Caballero from the ensuing kick-off when he caught Romain Sazy in the air, giving away just a penalty, rather than a yellow card.
Grant then gave the visitors the chance to get right back in it when he knocked the ball
on deep in his own 22, but La Rochelle got the nudge on in the scrum, and their rush defence forced Remi Lamerat into a knock-on.
The game was beginning to get fractious, with the visitors losing their cool and their focus as the game slipped away from them.
And the home side added their third try after 55 minutes with Castres looking out of ideas.
Alofa Alofa and Uini Atonio made ground down the left, before the ball came back to the right, and with an overlap, Murimurivalu stepped inside to go over for the try. Audy missed the conversion, but the Rochelais still led 34-16.
The visitors were being outplayed in every sector of the game, with their scrum crumbling in the second half.
But in the end it was a fumbled pass that proved costly, as Bobo collected the ball deep inside his 22 and showed he still has plenty of gas, even at 39-years-old, to race 90 metres for the bonus-point score.
For La Rochelle:
Tries: Barraque, Bobo 2, Murimurivalu
Conversions: Audy 2, Barraque
Penalties: Audy 4
Yellow Card: Atonio
Penalties: Kockott 3
Yellow Cards: Capo Ortega
La Rochelle: 15 Kini Murimurivalu, 14 Alofa Alofa, 13 Jean-Pascal Barraque, 12 Levani Botia, 11 Sireli Bobo, 10 Peter Grant, 9 Julien Audy, 8 Jone Qovu, 7 Kevin Gourdon, 6 Romain Sazy, 5 Cobus Grobler, 4 Jason Eaton, 3 Uini Atonio, 2 Hika Forbes, 1 Thomas Synaeghel
Replacements: 16 Rassie van Vuuren, 17 Mike Corbel, 18 Leandro Cedaro, 19 Nicolas Djebaili, 20 Julien Berger, 21 Hamish Gard, 22 Charles Lagarde, 23 Lekso Kaulashvili
Castres: 15 Julien Dumora, 14 Didier Combezou, 13 Remi Lamerat, 12 Romain Cabannes, 11 Remy Grosso, 10 Remi Tales (c), 9 Rory Kockott, 8 Jannie Bornman, 7 Yannick Caballero, 6 Piula Fa’aselele, 5 Rodrigo Capo Ortega, 4 Richie Gray, 3 Paea Fa’anunu, 2 Brice Mach, 1 Mihaita Lazar
Replacements: 16 Mathieu Bonello, 17 Saimone Taumoepeau, 18 Christophe Samson, 19 Ibrahim Diarra, 20 Cedric Garcia, 21 Romain Martial, 22 Dan Kirkpatrick, 23 Yohan Montes
Referee: Sébastien Minery