Northampton boss Jim Mallinder admitted that Saturday's crushing loss in Clermont was "one of the worst defeats I've experienced".
Clermont hammered Northampton in every facet of the Champions Cup quarter-final, knocking the Premiership champions out of the competition.
Saints currently hold a ten-point lead at the top of the Premiership but the mental effects of this loss will be scrutinised over the next few weeks.
Mallinder didn't shy away from where the game was lost while still believing his side are a top team, just not on Saturday.
"It's one of the worst defeats I've experienced. We've had a few shockers and that's definitely one of them," said Mallinder.
"We're disappointed because clearly we wanted to progress and have the chance of a home semi-final. We have to take this on the chin.
"We were well beaten. We came up against a very, very good side. Clermont played very well and we didn't. When you're losing 27-0 at half-time, that's basically game over.
"You come into these games knowing you have a chance, but that you'll have to play to your very best. We didn't do that and so were well beaten. Now our focus has to be on retaining the Premiership, it's as simple as that.
"We talked about needing to make a good start and shutting the crowd up, but completely the opposite happened.
"Clermont made a cracking start, put us under pressure and we clearly didn't compete in the first half in any of the areas.
"The set piece didn't function. The physicality wasn't there. We couldn't keep hold of the ball, spilling it too often. Our kicking and kick chase were also poor.
"The top French teams are very, very good. And at times we are very good, but not in this match.
"On this performance it would be hard to argue against it (there being a gulf in class), but we have competed against their top sides in the past."