Cullen acknowledged the high level of motivation within the squad as they prepare to face the reigning champions.
"Everyone's worked incredibly hard to get to this stage and it's amazing to be here now, but it's going to be a serious challenge," said Cullen.
"But it's what we want, to be at this stage.
So let's try and embrace the occasion and make sure we try to deliver our best performance," he said.
Cullen noted the ambition that drives the team throughout the season.
"At the start of the season everyone is thinking about getting to this point," said Cullen.
"There's a certain level of achievement to get to this point, but everyone wants to push on now," he added.
Cullen expressed immense admiration for Bordeaux's recent trajectory and domestic performances.
"We are fully respectful of the Bordeaux team and what they've achieved in recent times," said Cullen.
"But that's what you want.
You want to be able to test yourselves against the best, and Bordeaux probably have been the best team in Europe over the last couple of seasons," he said.
Cullen also shared his perspective on the value of the cross-border competition format.
"It's going to be a serious challenge but it's what we want, isn't it?" said Cullen.
"It's about trying to deliver our best performance, because that's what it'll take," he added.
Cullen voiced his support for maintaining the structural integrity of the tournament against critics.
"Hopefully the organizers protect it, because it's an incredibly special tournament," said Cullen.
