Castres closed in to three points off leaders Clermont after an uninspiring 15-9 win over struggling Bordeaux-Begles on Friday night.
Ahead of the weekend games, the champions overtook Stade Francais to go second, but they did little on this evidence to suggest they might retain their title in May.
Even so, it was a welcome return to winning ways, having seen a five-match unbeaten run ended at Grenoble last weekend.
“It wasn’t easy, but that’s what we expected,” Castres coach David Darricarrere said.
“We got the win, we managed to win a match that wasn’t easy. You don’t always get games with great moves and an attacking bonus,” he added.
For Bordeaux, the defensive bonus moved them to seven points above the relegation zone.
“A defensive bonus point against the champions of France is good, especially given the matches they had before and the scores they put on the teams who preceded us in this stadium,” Bordeaux coach Vincent Etcheto said.
The first half offered little to warm hearts on a chilly evening in Languedoc Province in the south of France, despite three yellow cards.
Argentine flyhalf Nicolas Sanchez gave the visitors a second-minute lead with a penalty, but two replies from left-wing Geoffrey Palis had the champions in front just past the halfway point of the half.
Castres spent large portions of the half camped down in Bordeaux territory, but rarely threatened to breach the whitewash.
Just past the half-hour mark Bordeaux lost the first player to the sin-bin as hooker Clement Maynardier was sent to cool down for 10 minutes.
However, when he rejoined the fray, Castres had themselves two men in the bin as both flanker Yannick Caballero and Palis had seen yellow.
That allowed replacement No. 10 Romain Lonca to level matters before the players headed into the changing rooms for half-time.
Castres avoided being penalized further while in numerical inferiority, while Scotland lock Richie Gray was proving a weapon in disrupting Bordeaux’s lineout, stealing two.
Once back on the field, Palis added two more penalties to Castres’ score before replacement Spain scrumhalf Cedric Garcia took over kicking duties and notched his own three-pointer.
Lonca had missed a pair of kicks at goal, so replacement scrumhalf Baptiste Serin took over and landed one from 45m out.
However, he was guilty of a curious piece of game management as Bordeaux kicked a penalty to touch deep inside Castres territory with time running out.
The final hooter had gone as Bordeaux’s forwards bashed away at the Castres defense, only for Serin to decide to settle for the defensive bonus and kick the ball out, much to the bemusement of many of his teammates.