Did Ireland fire its best trick shots too early?
Joe Schmidt's team scored Ireland's first home victory over the All Blacks in Dublin in mid-November, dominating the first half and doing enough in a more open second spell for a 16 – 9 score line .
It was not only a warning shot across the All Blacks bows, but revealed how the Irish might approach the All Blacks at the World Cup.
At the time, it seemed unlikely they would meet in the quarter-finals, with both teams favoured to top their groups.
But it was certainly not impossible.
For one thing, Ireland will now find it far tougher to catch the All Blacks out with the blindside plays.
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There were two significant ones and like just about everything Ireland do under Schmidt, they were pre-conceived, well thought out and no doubt practised to perfection.
The more memorable led to Jacob Stockdale's try, when inside centre Bundee Aki switched back towards the left wing who was confronted by the remnants of the All Black lineout. He chipped ahead and beat Aaron Smith's covering tackle, with Damian McKenzie arriving too late having been fooled by the initial direction of Ireland's move.
The All Blacks had an earlier warning about where Schmidt and his cohorts felt they could find a weakness.
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It was a brilliant move, timed to perfection from an Irish ruck near the All Blacks 22.
Forwards James Ryan, Peter O'Mahony and Devin Toner lined up shoulder to shoulder on the openside, with centre Garry Ringrose glued to them on their inside.
But as soon as halfback Kieran Marmion's pass hit Ringrose, he veered sharply back to the blindside, and linked with Josh van der Flier, who fed right wing Keith Earls who made a dangerous jinking run.
The ruse worked because it lured Jack Goodhue towards the openside, leaving a big blindside hole which Ryan Crotty just managed to cover as Goodhue hastily headed back to the danger area.
Were Ireland so desperate for a morale-boosting win over the All Blacks that they were prepared to dig deep into their bag of tricks? Surely Schmidt must feel that he can produce other moves which expose the famed All Black defence.
There is one Irish tactic which the All Blacks will find much harder to counter.
Schmidt loves to get a runner angling in front of the first receiver ballplayer, heading towards two inside defenders.
In days long past, it might have been seen as an illegal blocking move.
The path of this decoy runner holds up the inside defenders, who are set on their heels and find it harder to keep the line intact. The decoy also likes to end up in a place which partially blocks the defenders, creating a half gap.
It was only great desperation and awareness from All Black captain Kieran Read, who swam around decoy Josh van der Flier's guard work, which prevented Johnny Sexton from cutting loose early in the second half.
Ireland battered the All Blacks with powerful ball runners close to the ruck in the first half, and it's hard to see them going away from this tactic given that their game has not evolved in different directions. The wider Ireland went, the clunkier they looked.
They also intermingled their forwards and backs, whereas the All Blacks were more inclined to use a traditional backline with maybe one forward in the attacking line.
Watching that game again, it is also easy to see why there are claims the All Blacks use a system of illegalities to break up opponents' momentum.
Taking certain incidents in isolation, it could be said that a player like Sam Whitelock didn't show enough patience. Taken as a whole, the All Blacks display a certain pattern in that regard.
"Next one to the bin," referee Wayne Barnes warned Kieran Read late in the first half.
In comparison, it has to be said that the All Blacks revealed very little, although they did use the Beauden Barrett-Richie Mo'unga act late in the game.
In a very un-All Black moment, Barrett landed a first-half drop goal rather than go for a try when playing under penalty advantage. This seemed to sum up a side playing within themselves, late in a long season.
That Ireland could play so well yet win by only seven points at home against a tepid All Black effort would seem to bode well for New Zealand's quarterfinal chances. The magnificent Irish crowd, which falls impressively silent during shots at goal, also played a big part, stirring their side on to victory.
That is not to take Ireland lightly in Tokyo, far from it. Their pack is physically strong and dynamic, and they hunt with and without the ball in muscular little units. They won that game without star halfback Conor Murray, who will be a pivotal figure this weekend.
The Irish loose forwards were outstanding in Dublin, as were starting props Cian Healy and Tadgh Furlong.
In contrast, veteran All Black tighthead Owen Franks was quiet, and Karl Tu'inukuafe a virtual passenger around the field. Their scrum work didn't start well either.
It may have been the day when coach Steve Hansen realised the front row changes he was probably already contemplating were absolutely essential for Japan.