With Leinster through, 14 sides remain in contention for seven quarter-final places.
It also promises to be a depressing one for the Premiership. A scenario exists whereby no English sides make the last eight.
The swirling mathematics of the most complicated weekend on the rugby union calendar make it hard to predict with any certainty – but a total Anglo wipeout is by no means far-fetched.
Exeter may yet keep the flag of St George flying, as could – in decreasing order of probability – Bath, Saracens and Wasps.
But when the dust has settled on Sunday night, Europe is likely to look a pretty bleak landscape for the English.
If the Scarlets produced arguably the performance of the season in sweeping aside Bath 35-17 at The Rec last Friday, Leinster have been the team of the season, winning all of their games. Saracens, by contrast, have won only two of their five in Europe.
The other English sides have been equally hit and miss or, in the case of Leicester, whoare likely to supply four of England’s starting line-up for their opening game against Italy, just miss.
Ben Youngs and George Ford, rested for the embarrassing 39-0 whitewash in Castres on Sunday, could do with finding some form against Racing in Sunday’s dead rubber.
Few coaches have the ability to inject confidence into players like Eddie Jones but his Australian bravado can only cover so many cracks.
Players thrive in teams that are playing well. In Europe, no English team has played consistently well this season.
The Premiership clubs’ collective failure, if that is how it turns out, cannot be down to money. The French still have the most euros but with the salary cap raised to £7 million, the English spend more of it (which is different to having more of it) than the Irish provinces or the Welsh regions.
Injuries, of which Billy Vunipola’s is only the latest, have played a part with the Premiership’s attrition rate at an all-time high. That sort of money should buy cover in a squad despite the unusually high injury rate this season.
But linked in is the inferior management of the country’s – and the clubs’ – best players.
Flogged by the Lions in the summer and Jones when he gets his hands on them by England, the clubs demand their pound of flesh too. While Ireland’s landscape for the English.
The knock-on effect for the Six Nations should be a concern.
England have won the last two championships, the first with a Grand Slam, with a side constructed around the all-conquering Saracens team that won the Champions Cup in those seasons. This time it is round three.
Should any of the Premiership clubs reach the Champions Cup quarter-finals, which fall a fortnight after the end of the Six Nations, the same situation will arise. The Irish players, contracted centrally to the IRFU, will be given the weekend after the Six top players, who started the provincial season a month late, enjoyed the luxury of a rest week after the autumn Tests, England’s internationals were straight back at it after the autumn Test.
The result? Defeat for every English side for the first time on a European weekend in Nations off; the English players, owned by the Premiership clubs, will be required to shoehorn in a league game.
The relentless workload has taken its toll on English clubs; the danger is it could also impact on England.