Since then Vunipola has become a victorious British & Irish Lion, featuring in all three Tests Down Under last summer.
And the 23-year-old is adamant that now is the time for he and his teammates to prove just how far they have come.
"We knew that day (in 2012) we got beaten up, well and truly, and we know European rugby is a step up from the league," he said.
"So for us as a team we know we have to front up to them and match them physically really.
"Clermont are a good side but any side obviously has some flaws and we know we're going to have to try and work hard to find them.
"We're definitely looking forward to the game. It's been a long year and one I've enjoyed so far and hopefully Saturday will be an awesome game."