And the Welsh coach is under no illusions that a second consecutive Heineken Cup win is in the bag.
"We know we have to be better," said Young. "We are expecting a real tough physical battle and Castres are very strong at scrum and lineout time.
"If they get on the front foot they can really rumble forward.
"It's a physical challenge for us but one we will relish and not run away from.
"France is always a difficult place to play and to get a result.
"If you play below your best you won't get the win. We know opportunities are going to be few and far between next weekend and we have to make sure the scoreboard ticks over."