STALWART Julien Dumora says that knockout rugby has already started for Castres as they prepare to host the Dragons in the European Challenge Cup.

The 2018 French champions trail Dean Ryan's men but are in control of their destiny with Saturday's clash at the Stade Pierre-Fabre followed by a trip to Worcester.

Win both and Castres will top Pool One, fail in either clash and they will miss out on the quarter-finals.

The French side have a proud home record in Europe - Exeter, Munster, Gloucester, Leicester, Racing 92, Leinster, Northampton, Montpellier and Pau have all failed to leave with the spoils over the past four years.

Full-back Dumora, who has played for the club since 2011, wants to stay alive in the group by extending that streak.

"It's a do-or-die encounter. If we win, we maintain our hopes of qualifying. In contrast, if we lose, it will be difficult for us to reach the knockout stage," he said.

"It's a real play-off match. The knockout stage of the Challenge Cup starts this weekend for us. We need to step up our motivation levels."

The Dragons took the spoils 31-17 when the teams met in Newport in October thanks to a Taine Basham hat-trick, a score by wing Daf Howells and a determined defensive effort.

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"They will be coming to Castres looking for a win and to qualify," said Dumora. "We know what to expect. They will not want a fruitless journey.

"All our squad are well aware that it will be a hard match. But we are ready to continue this adventure.

"In the away game we clearly saw that they have a pack who are good in the collisions. They hurt us a lot in the driving mauls, scoring two tries.

"They will come with the same frame of mind, but we are committed to giving them a warm welcome."

Castres' prime concern is avoiding a relegation dogfight in the Top 14 after a worrying recent slide down a congested table.

They are just a win away from eighth place but just three points clear of second-from-bottom Stade Francais.

It's unlikely that the first team will travel to Sixways but Dumora insists Castres aren't concentrating on the league.

"We had a clear aim at the start of the season. We wanted to qualify from this pool for the quarter-finals," he said.

"We still have our destiny in our hands. I really feel this team will give every last drop in these last two matches, so that there are no regrets.

"The Challenge Cup is very important to the club. It's a great competition with some big teams."

The Dragons have a two-point lead over Castres and a five-point advantage over Worcester.

Dean Ryan's men, who finish against Enisei-STM at Rodney Parade, need to win to stand a chance of earning a home quarter-final.