The last two tests in Dublin between the All Blacks and Ireland have been epically physical, but ultimately determined by the influence of the respective No 10s.
In 2018 it was Johnny Sexton who could do no wrong, masterminding Ireland's greatest 80 minutes against New Zealand to steer themto a 16-9 win and himself to the World Player of the Year crown.
Two years earlier it was the Beauden Barrett show. It was a game defined by the brutality of the collisions and the majesty of Barrett who scored a try, made a try and saved a try.
The test this weekend is effectively the decider, an opportunity for two great playmakers who, in a statistical quirk will both be playing their 101st tests, to see who can better exert their will and have greater impact on the game.
There's perhaps a bigger picture at play, though – one that says this test is a chance for one or other to establish themselves as the greatest and most influential first-five in the post Dan Carter-era.
Barrett and Sexton have between them been crowned World Player of the Year three times in the last five years and are the two No 10s that have delivered the consistency and magical touches which separate them from other fine players such as Dan Biggar, Owen Farrell, Finn Russell and Richie Mo'unga.
Both could claim they have been the world's premier No 10 since Carter retired in 2015 and a head-to-head contest is at least a symbolic if imperfect means by which to determine a winner.
Beauden Barrett scores a try despite the tackle from Ireland's Johnny Sexton during the 2016 test. Photo / Photosport
It says something highly significant about a first-five's mental resolve and composure if they can deliver their best performances when the pressure is at its most intense and the stakes at their highest.
Equally, it says just as much if there are two great No 10s on the park, but one obviously has the means and desire to out play the other and own the contest.
Back in 2016, what made Barrett seem to be so far ahead of Sexton was the try he scored direct from a scrum, just inside the Irish half.
Barrett roared on to Aaron Smith's pass and then accelerated through the Irish defence without a hand being laid upon him until Sexton, covering back, high tackled the All Black No 10.
It was yet another unbelievable moment from Barrett in what had been an unbelievable year and the way Sexton was reduced to such a crass means to try to stop his opposite number illustrated that he knew he was competing against someone he couldn't match.
Two years later and what stood out was Sexton's composure and tactical reading of the game. Where he seemingly played with inordinate time and space, making smart and effective decisions, Barrett was hurried and often isolated.
Johnny Sexton and Beauden Barrett are set for another epic battle. Photo / Photosport
The symbolism of these head-to-head meetings matters because they often produce cameo moments that reveal a picture no one was previously seeing or confirm what everyone thought they already knew.
Arguably, the tests in 2016 and 2018 confirmed more than they revealed in specific regard to Barrett and Sexton, but the picture in 2021 is not so clear as to which of the two is likely to come out on top.
Barrett has been mostly steady this year, his game carrying a greater element of solidity through a higher volume of percentage plays.
It would be misleading to class his work as perfunctory, but his portfolio to date is missing a quintessentially Barrett performance defined by his speed, running lines and ability to pull off the improbable.
The signal that Barrett is back at his best will be when he rips a team apart with his blinding acceleration, turning their well-planned defence inside out with his running game.
There's a sense that Barrett has been building towards a memorable performance – one where he reconnects with his old self and plays with no inhibition or fear.
Beauden Barrett celebrates. Photo / Photosport
Dublin feels like the place it might happen: this test against Ireland the one where Barrett busts out the free spirit within himself and delivers the sort of performance that came so easily to him in 2016.
If he goes all classic Barrett, he'll not only fend off the internal threat of Mo'unga, but also establish that he and not Sexton is the rightful heir to Carter's vacated throne.
Not that Barrett will be driven by personal glory. Why this game might be the one where he erupts is that it will have a massive bearing on how the All Blacks 2021 season ends up being assessed.
Given the toughest schedule in modern history, the All Blacks are sitting on 12 wins from 13 tests.
Beat Ireland this week and France next and they will finish the year with just one defeat and an undeniable sense they are back on top of the world.
