The acid tests await, for the Scots against South Africa at St. James' Park in Newcastle on Saturday; for the Irish against France in Cardiff the following weekend. The outcome will determine their fate, not merely in terms of qualification for the last eight but where they go and who they run into.
Ireland, aiming to go further at this Rugby World Cup than they have gone at any of the previous seven, will not fail for any lack of support. In the course of turning Wembley into forty shades of green against Romania on Sunday, they duly helped break the tournament's all-time attendance record set by New Zealand and Argentina.
Those two held it for all of seven days before the Irish and the Romanians raised the number by 248 to a new high of 89,267. Nobody will beat that for a very long time because Wembley has staged its two matches and no other venue can quite match its capacity.
Ireland duly marked the occasion by picking their match-day 23 en masse from the GUINNESS PRO12, as per usual - five from Munster, five from Ulster, one from Connacht and the remainder from Leinster. Six more tries took their tally to 13, profitable preparation for the big one against France.
Scotland, whose five tries against Japan eliminated any danger of another giant-killing, relied on ten Glasgow Warriors and six from Edinburgh in the process of running in five more against the American Eagles at Elland Road.
A few hours earlier, Wales drew on the same number from all four of their regions for their momentous win over England. Twickenham had witnessed many unforgettable moments in the rich and occasionally brutal history of Anglo-Welsh contests but never anything like last Saturday night.
When Wales were crying out amid the bedlam of the final ten minutes for some inspiration, three players duly provided - first to save the match, then, incredibly, to win it.
All three ply their trade in the GUINNESS PRO12. Nobody could have dreamt up a finale that almost defied belief because imaginations, even of the most fertile variety, do not stretch that far.
A substitute scrum-half on the left wing finding an ocean of space where none had existed for the previous hour with one flick of his left foot? Lloyd Williams executed it so perfectly that the other scrum-half, Gareth Davies, could gather it without checking his stride to score between the posts.
And just when Wales would have been thrilled to get away with a draw, the chance then presented itself to go one better and seize four Rugby World Cup points instead of two.
Dan Biggar had a tough enough job to do running the game at fly-half without wasting any nervous energy about following the hardest goal-kicking act in the game to boot. Those who fretted over Leigh Halfpenny's cruel removal from the competition tended to underestimate Biggar's consistency off the tee, as honed in the GUINNESS PRO12.
A percentage success ratio in the high 80s put him in a class of his own. When the chips were down four minutes from time at Twickenham, the unflappable Osprey cleared the bar from just inside the English half with distance to spare when some feared it might have been beyond his range.
Just as he never looked like missing any of the six previous shots at goal, Biggar's seventh may yet change the course of Rugby World Cup history. It means that England will almost certainly be knocked out unless they beat Australia at Twickenham on Saturday.
For Wales, all that matters is ensuring they put their fragmented bits back into one piece in time for Fiji at the Millennium Stadium on Thursday. By contrast, Ireland have escaped any serious blows, less so Scotland.
They will have to manage without Grant Gilchrist. As if the Edinburgh lock has not suffered enough anguish, the groin injury behind his early exit from Elland Road is bad enough to prevent him taking any further part in the competition.
Last year, as Scotland's newly-appointed captain for the annual autumn series, Gilchrist broke his arm in a European club match before he could lead his country. Complications then destroyed any hope of a come-back during the RBS 6 Nations and, worse still, wiped out the entire season.
The success of GUINNESS PRO12 players has not been restricted to the Irish, Scottish and Welsh. Zebre centre Gonzalo Garcia touched down for Italy in their win over Canada but not before another Guinness PRO12 back had engineered an early contender for try of the tournament.
DTH van der Merwe, a title winner with the Glasgow Warriors in Belfast last May, followed his long-range solo try in Canada's opening Rugby World Cup tie against Ireland in Cardiff with another, even more stunning effort against Italy which he started and finished.
A South African who emigrated with his family to Saskatchewan 12 years ago, van der Merwe switched clubs during the summer, from Glasgow to Llanelli. No wonder the Scarlets can't wait to get him started…
The Rugby World Cup and how they rate out of ten after two rounds of the pool competition:
10 out of 10: Ireland, Scotland
9 out of 10: Wales, Australia, New Zealand, France
7 out of 10: South Africa
6 out of 10: England
5 out of 10: Argentina
4 out of 10: Japan, Samoa, Georgia, Italy
1 out of 10: Canada, Tonga
0 out of 10: Fiji, Namibia, Romania, USA, Uruguay
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