Castres, who freely stated this week that their focus is now firmly on the Top 14, have nevertheless named a strong side for the trip to Watford.
Charlie Sika returns to the centres and there's a return for international flanker Ibrahim Diarra in a reshuffled back row.
There's also a spot for experienced lock Rodrigo Capo Ortega ahead of Russian international Kiril Kulemin and a completely new front row in Daniel Saayman, Georgian international Aksventi Giorgadze and Yannick Forestier.
More to follow...
Castres: 15 Thomas BouquiÃ©, 14 Matthieu Bourret, 13 Charles Sika, 12 Philip Christophers, 11 Paul Bonnefond, 10 Romain Boscus, 9 Thomas Sanchou, 8 Joe Tekori, 7 Darron Nell, 6 Ibrahim Diarra, 5 Ludovic Michaux, 4 Rodrigo Capo Ortega, 3 Daniel Saayman, 2 Akvsenti Giorgadze, 1 Yannick Forestier.
Replacements: 16 Marc-Antoine Rallier, 17 Gideon Lensing, 18 Yoann Rayssac, 19 Kirill Kulemin, 20 Yannick Caballero, 21 Alexandre Albouy, 22 Yoan Audrin, 23 Maxime Boyer.
Date: Saturday, December 19
Kick-off: 20.00 GMT
Venue: Vicarage Road
Referee: Peter Allan (Scotland)
Assistant referees: David Changleng (Scotland), Rob Dickson (Scotland)
Television match official: John Burtenshaw (England)
Assessor: Roger Baileff (England)