Cullen faces balancing act in Europe's business class
Montpellier 14 Leinster 23
When Stuart Lancaster and Leo Cullen review Leinster's record-breaking pool journey - the 27 points haul took them past their previous best of 26, in season 2004/05 - the list of things to improve on will be short enough.
You don't finish as number one seed in this competition without having very sound fundamentals.
If you can load some X factor on top of that, and supplement it with an ability to climb out of a hole, then the bookies are certainly going to consider you short odds - at least for the final day in Bilbao, never mind your home quarter-final.
The uphill bit for Leinster here was dealing with being overhauled after a fine start.
They went ahead through a Ross Byrne try and penalty, but conceded two tries, and the lead, to the powerful Montpellier maul.
The X factor on this occasion was double barrelled: Jordan Larmour, who was more solid than spectacular, which was no harm; and James Lowe, who was part sublime, part skittish.
So Stuart Lancaster will have some fine tuning to do with the Kiwi. And Leo Cullen can start figuring out how to optimise the transition of Ireland's Test players back into the Leinster fold post Six Nations - a recurring issue for those lucky enough to be at Europe's business end.
"We've looked at various different strategies so we'll see when the quarter-final is and try and make a plan based on that, but it's that balance about trying to make sure guys are fresh, because playing those five games in the Six Nations does take its physical toll as well," Cullen said.
Man of the Match Sean Cronin will be one of those needing to get back on Leinster's wavelength at that point. Given that he was surplus to Ireland requirements in November, things have turned around for him.
"I'm happy enough," he said.
"I just think I probably didn't get going at the start of the season and I'd been unfit when I came back. Id played three games in nine months.
"I didn't get into the November Tests, which was probably fair enough as I hadn't been playing to my potential. I got a good chance to go back and work with the S&C guys here and with Leo and Stu giving me a chance over that November period to play.
"I was really happy and that got the ball rolling."
It's that way for them all.
It says something about your form when the opposition - a team loaded with international talent - have stopped looking for weaknesses in your game and instead are focusing solely on what they can do themselves.
"They're brilliant," Ruan Pienaar said after the final whistle in Altrad Stadium.
"I think they all know their roles within the team and how they want to play, so I think that's the key to them. No matter who comes in, whether it's a youngster or a guy who's been there for six or seven seasons, they know what to do to get the job done.
"I've played with Ulster and seen the way that Leinster operate. They're well organised and everyone knows their roles.
"I think they stick to their structures no matter what the score is and they execute that well. This is a really good Leinster team with a lot of good youngsters coming through again and then some of the older guys have been around a long time.
"They've got a really good squad with a lot of depth and that shows in their form."
It was interesting that despite having overhauled an eight-point deficit to lead 14-8 at half-time - a try-saving tackle by Tadhg Furlong on Nemani Nadolo kept it at that - Montpellier never felt that they had turned a corner in this game.
Although they were the home team, they didn't look like they were about to kick on - and certainly not unless it involved Aaron Cruden knocking a penalty into touch and then letting his massive pack grunt their way over the line.
"I don't think we ever felt like we were in control," Cruden conceded.
"We felt like we were in with a sniff, in the hunt. In that second-half, in those pressure moments, they knew exactly how they wanted to play the game.
"They executed pretty well and put us under pressure and we just didn't quite cope with that well enough.
"If we want to compete at the highest level in Europe, we're going to have to take the learnings from that match out there and put those into practice."
Once Leinster hit the home team with tries from Robbie Henshaw and Cronin, either side of a Ross Byrne penalty - all in the space of a stunning six minutes in the third quarter - it was effectively game over.
For Leinster, though, this is just the beginning.
The challenge for them from this point is to maintain fitness and focus, and getting them all back up to speed in the gap between the Six Nations and the Champions Cup restart in the Aviva.
All the other bits are coming together nicely.
Montpellier: B Fall; T Nagusa (J Mogg 56), F Steyn (J Tomane 67), J Serfontein, N Nadolo; A Cruden, R Pienaar (G Aprasidze 76); M Nariashvili (Y Watremez 60), B du Plessis (R Ruffenach 60), A Guillamon (M Hamouas 64), NJ van Rensburg, K Mikautadze (J Delannoy 73), K Galletier, L Picamoles (capt), Y Camara (F Ouedraogo 60)
Leinster: R Kearney (J Carbery 58); J Larmour, R Henshaw, I Nacewa (capt), J Lowe (F mcFadden 69); R Byrne, J Gibson-Park (L McGrath 58); C Healy (J McGrath 45), S Cronin (B Byrne 66), T Furlong (A Porter 66), D Toner, J Ryan (R Molony 73), D Leavy (J Murphy 67), J Conan, J van der Flier
Ref - L Pearce (England)