A defeat at Castres in 2008-09, to a clearly inferior side, was seen by many as an unacceptable manifestation of the 'same old' Leinster, but it proved to be a turning point for Michael Cheika's team in their run to a maiden tournament victory.
This season's visit was an altogether different story, however. Leinster's progress through the pool has been more straightforward than expected, with a disappointing show from Northampton and Montpellier's capitulation last week. That 57-3 victory at the RDS reset the benchmark for Leo Cullen's side and constructed a platform for future performances.
The confidence within the squad is palpable. While the younger cohort of Tadhg Furlong, Josh van der Flier, Adam Byrne and Rory O'Loughlin have been grabbing headlines, the leadership and performance levels from the likes of Johnny Sexton, Isa Nacewa, Devin Toner and Jamie Heaslip have been no less eye-catching.
Driven by Sexton, the manner in which they have dictated tempo from the outset of recent games has been especially striking, with skipper Nacewa looking close to his best of 2011. The early loss of both through injury on Friday night not only underlined their importance to the side but also provided their young colleagues with one of the bigger challenges of their fledgling careers.
Not even close physically to the biggest teams in the competition, Leinster have recently been playing to their significant strengths in pace, fitness and ball-skills. Without their star men, however, it was much more difficult to bring these qualities to bear. Timing, in both attack and defence, was more than a little awry and it didn't help either that the bounce of the ball, so much in their favour last week, went against them this time.
While the kick will always be a part of the wider attacking repertoire, the recognition of the need to tire defences has been encouraging to see, in the context not only of this squad's development, but also a resumption of Leinster's traditional way of playing. On Friday's evidence, however, their capacity, in the absence of Sexton and Nacewa, to apply the levels of pressure required at the highest level is, at best, questionable.
Regardless of the changes wrought on the game over recent years, the hostility facing an away team in the south of France, particularly for an evening game, should never be underestimated, and the scrum is the battleground of choice for all home efforts in this regard.
Leinster's restructured front-row, with Cian Healy and Richardt Strauss returning, conceded little but didn't manage to assert any superiority either.
While the ball-carrying abilities of Furlong, Heaslip and, more recently, Jack Conan have been laying the foundations for Leinster's attack this season, it's the quality of their back-play that has been the hallmark of the team's improvement. In recent years, the bluntness of the attack generally, and especially the quality of passing, had been widely cited as symptomatic of a gradual overall decline.
Sexton's return, coupled with the emergence of Robbie Henshaw and Garry Ringrose as a partnership of real class in the centre, has brought a new dimension to the backline, and the out-half's absence for most of Friday night's game was keenly felt.
For all the promise of Ross Byrne and Joey Carbery, Sexton's absence leaves a play-making void that no team with realistic aspirations to success at the highest level can afford.
The levels of expectation surrounding Leinster were evident in the disappointment following an away draw with one of France's strongest sides. You can't escape a sense that they have coughed up a great position in the competition, an opportunity lost: nailing down a home quarter-final in style, rather than waiting on other results, would have sent quite the message.
Even allowing for Friday's disappointment, however, momentum is undoubtedly behind both themselves and Munster.
The health of the returning international contingents, particularly Leinster's, at the conclusion of the Six Nations could well be of even greater importance than the coveted home advantage in the knock-out stages.
Nacewa's team will learn a lot from Friday night's experience and those young players will be much the better for it. If their home tie does materialise, no team in the competition (except Munster, of course!) will savour a trip to Dublin and, at this point, anything is possible.
Sunday Indo Sport