Captain Chris Robshaw says Harlequins will have to "front up" to mighty Clermont this weekend if they want to keep their Heineken Cup campaign alive.
Quins are four points behind Clermont in Pool 4 and if they win at The Stoop in Saturday's mouth-watering showdown they could go top, with just one more match to play in the group phase.
In the reverse fixture in France back in October, Harlequins were blown away in the first half, conceding three tries to the hosts.
But they clawed their way back into the match after the break and deep into injury time Nick Evans calmly slotted a superb drop goal to give Harlequins a losing bonus point.
Clermont won the game 23-16, but the precious point effectively kept Harlequins in the competition.
If they reach the quarter-finals, they will become the first team to do so having lost their first two matches.
"It was a game which got our season back on track when we went over to Clermont," Robshaw told Sky Sports.
"We'd had a slow start to the season but we went over and gave it a good go.
"And we managed to come away with a very valuable bonus point."
Clermont are all-but invincible at home, unbeaten in over 70 matches but away from home they remain vulnerable, particularly outside France so Harlequins will go into the match confident but not, Robshaw, says, underestimating how tough a challenge they face.
Clermont have a monster pack and pace and power behind it. It was a bruising, physical battle at the Stade Marcel Michelin, and it is likely to be again at The Stoop.
"We know how dangerous Clermont can be. I think they scored three tries in 15 minutes (in France). So we really cannot afford to switch off this weekend. And we have to front up physically," Robshaw added.