Saints' win in Belfast over Ulster rekindled ambitions of qualifying for the European knockout stages. But Castres are coming to the Gardens still very much in the hunt themselves and Waldouck says that it is going to be a physical challenge.
"It's a huge match for us in the competition," he said. "We're still alive and kicking in the Heineken Cup and hopefully we can take the momentum into the game from the win over Exeter.
"They'll be a big challenge for us and we want to get our home form back up and running.
"French teams are always passionate, and Castres have a lot of quality players in their outfit. So we'll have to be on the money to get the result we want. Everyone's aware of the physical challenge and what the game means to us as a team.
"We'll bring a lot of passion and hopefully that will turn into a decent result.
"The fans really spurred us on in Milton Keynes and were great at Sandy Park, too. The support at home is always huge in motivating us and when it is rocking Franklin's Gardens is a great place to play."
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