LONDON -- Twickenham sets the scene for the make or break of the All Blacks and England's season.
Two teams delicately poised, yet to fully convince, on a one-way collision course to define their respective 2025 campaigns.
Another blockbuster awaits.
All Blacks coach Scott Robertson needs to all but clinch the Grand Slam to provide definitive evidence of his tenure's progress.
The All Blacks arrive at Twickenham having won four in a row, nine from 11 this year, and yet the manner in which they defeated Ireland and Scotland in the last two weeks leaves nagging doubts.
There's also the ball and chain the All Blacks must shed that is their maiden loss in Argentina, and their heaviest defeat in history to the Springboks in Wellington, earlier this year.
Maintain their recent dominance against England to surely seal their first Grand Slam in 15 years - Robertson's men finish the year next week against Wales who last week shipped 50 points to the Pumas - and the All Blacks can dismiss doubt surrounding their improvements.
Lose to England, though, and those dark cloud doubts will hover over Robertson's head.
In many respects the complexion of the All Blacks' wins over Ireland and Scotland hangs on the result at Twickenham. Three tries in the final quarter blew Ireland away in Chicago but, for 60 minutes, the All Blacks struggled to string any attacking continuity together.
Last week at Murrayfield the All Blacks were seemingly on course for a statement performance, leading 17-0 at half time, only to collapse through a combination of yellow cards and sloppy skills.
Stoic goal line defence and Damian McKenzie's match-winning cameo off the bench, where he kicked a 50-22, scored a try that defied physics in the corner and slotted a late long-range penalty, saved All Blacks' blushes to preserve their 120-year, 33 match unbeaten record against Scotland.
But with their shaky work under the high ball, kickoff receptions and discipline in the spotlight, the All Blacks must vastly improve to halt England's new-found momentum.
More so than any other time in recent memory the All Blacks, certainly through an English lens, are viewed as vulnerable.
That England start favourites with the bookies this weekend, despite the All Blacks savouring a five-match unbeaten run at Twickenham, speaks to the unconvincing nature of Robertson's progress to date.
The All Blacks missing five players through injury - experienced forwards Tyrel Lomax, Tupou Vaa'i and Patrick Tuipulotu as well as starting backs Jordie Barrett and Caleb Clarke - is another contributing factor.
"We've got some good areas of our game we've got a little bit of confidence in at the moment which is pleasing but by no means are we satisfied with where we're at so we're looking forward to stepping up in a helluva contest," All Blacks forwards coach Jason Ryan said this week in London.
"I'm sure we've got a couple of weaknesses they've seen. Good on them if they've got confidence we have too. That's what you want from all your players when you go out in the fiercest arena.
"They've evolved immensely, and we have as well. They've changed how they like to break teams down. They've used the 6-2 split on the bench and found a bit of identity there and that's potentially working for them.
"England are on a bit of a roll and we've got a bit of confidence as well. It's all set up for a heck of a Test match."
Riding a nine-match unbeaten run England are, indeed, confident. They, too, though, need a significant southern scalp to confirm their credentials or their hype could swiftly fade.
Their winning streak, since losing their opening Six Nations match to Ireland, includes France but England haven't beaten the All Blacks for six years and the Springboks for four.
Lose on their sacred home turf, where they last defeated the All Blacks in 2012, and England's progress will be widely questioned.
The gap between the Springboks and the rest appears to be mounting after the world champions survived Lood de Jager's red card to surge over the top of France for an impressive success in Paris last weekend.
The winner of the All Blacks and England can probably claim second place in the unofficial rankings, while the loser will slide back to the congested pack with everything to prove.
England's last win against the All Blacks came in the 2019 World Cup semifinal, with Robertson presiding over three of New Zealand's last four successes in a row.
Those recent results are somewhat misleading, though, with England blowing the opening Test of Robertson's reign in Dunedin and ruing George Ford missing a late penalty and dropped goal this time last year at Twickenham.
"When you look at the recent history of our Test matches they've always come down to small margins at the end of games," Robertson said. "History and how you've done it matters. We'll talk about what it's like to play at Twickenham and the occasion of it all.
"It's pleasing you can hang tough and find a way. You can draw on the belief side of it but this Test match you've got to start again."
There's not just a Grand Slam at stake for the All Blacks this weekend.
Claiming that prize represents progress, stagnation or possible regression.