Leinster full-back Isa Nacewa is aware of the tough task facing his team when they take on Clermont at the Stade Marcel Michelin on Sunday.
The defending champions will be aiming to extend their unbeaten run in Europe to 18 matches when they head to France to face the Pool Five leaders.
Interestingly, it was against Clermont two seasons ago when Leinster suffered their last defeat in the competition (20-13). Since then they have won 16 and drawn one, with two triumphs coming over the French club - including last season's semi-final win.
That semi-final victory, however, was picked up at the Stade Chaban-Delmas. This time around though, Leinster will run out at the Stade Marcel Michelin where Clermont recently won their 50th consecutive game.
"Fifty matches. It's a tough place to go," said Nacewa.
"Awesome support, awesome crowd.
"They're the strongest team on paper, so many international caps and it's going to be a big one.
"What they call their second string side still has hundreds of international caps each week. This is a one-off game as a rugby player you get to play."
Both clubs won their two opening matches in this season's tournament, but Clermont managed to pick up winning bonus points in their victories over Exeter Chiefs and the Scarlets to lead the Pool by two points.
Leinster pipped new boys Exeter 9-6 on the opening day of their defence of the title and then won 20-13 at Parc y Scarlets.
Now comes their biggest challenge of all as they try to stay on course to become the first team to win three titles in a row.