Now the double Amlin Challenge Cup winners, who celebrate their centenary this season, clash with Pool 4 leaders Ulster Rugby at Stade Marcel Michelin on Saturday well aware they must both win and also deny the Irish club anything from the contest if they are to go through automatically as group winners.
Ulster, who won the Round 1 match at Ravenhill16-11, hold a three point advantage and a draw would be good enough to earn them back-to-back quarter-final qualification.
"We had a glimpse last November of just what Ulster are capable of achieving but they have evolved since then," said Rougerie.
"We already know they are great battlers and physically strong so, on that level at least, we will have to measure up, then we have the remainder of this week to put our tactics in place.
"Playing at home at Marcel Michelin this time will certainly be a massive advantage.
"Our fans are always behind us, pushing us, and that will be key when we play such an essential game of our season.
"However, we won't dwell upon calculations to study all the possibilities for us to qualify. We will go forward and try to win that tough game to start with and then, if we get five points, that would be great but it seems complicated in my view.
"We will see how the game pans out and play accordingly but most important of all we have got to get those important four points if we want to qualify at all, whether it is for a home quarter-final or an away match."
Clermont have reached the Heineken Cup knock-out stages three times but never made the semi-finals and Rougerie is aware that to make it four times they will have to get the better of an Ulster team in prime form after their 41-7 rout of Leicester Tigers.
"We will prepare this week bearing in mind that Ulster gave Leicester Tigers a rough ride in Belfast at the weekend, so that speaks volume of their form," he said.
"Saturday's game will be a totally different situation from last weekend in Italy because we will be facing another type of team - on this occasion a really tough one.
"We will have to show the same level of concentration that we produced in Monza - if not more - and we must ensure we that there is no relaxation after such a performance in Italy, that we focus on our drills and not lose that energy that we have at the moment.
"We've got to resume work straight away, we will analyse video footage to make sure we do things right against a very complete Ulster team because we expect a huge encounter.
"We had spent a very industrious week of preparation ahead of the game against Aironi because we expected that it could turn out to be one of those typical banana skins.
"We didn't want to leave anything to chance, it was important to be well prepared and to be as serious as possible to go to Italy.
"After the match we felt relieved, our performance was so reassuring, and we enjoyed playing out there and we came back with the five points we had targeted. It allowed us to build up some confidence within the group and it is a good thing ahead of such a crucial game against Ulster."