Three leading World Cup contenders – New Zealand, England and Wales – have something in common. They have all adopted the tactic of using twin openside flankers in their starting team.
The All Blacks could take that even further in the coming weeks by embracing three fetchers in their 23-man match-day squad.
Eddie Jones has impressive Bath flanker Sam Underhill and Tom Curry successfully working in tandem for England, while Warren Gatland combines workaholic duo Josh Navidi and Justin Tipuric when Wales are at full-strength.
Australia, while not considered one of the main contenders for the title, also employ David Pocock and Michael Hooper.
The All Blacks, of course, switched Ardie Savea to the side of the scrum this year to work in unison with Sam Cane.
Rather than select a sizable alternative on the bench, as those other teams have done, they may instead prefer Matt Todd over Shannon Frizell's physical presence for the big matches to come.
The All Blacks first surprised with this three-pronged openside approach for the loss against the Wallabies in Perth, and the 36-0 whitewash that followed at Eden Park.
While they may tweak the balance of their loose forwards depending on the opposition, it would not surprise if they again stockpile their fetchers for this weekend's final pool match against Italy, or next week's quarterfinal.
"We've all got different strengths and hopefully the way we're playing we can complement each other along with Reado (Kieran Read) as well," Todd said earlier this tournament. "Hopefully they continue to use three opensides in the 23 and I get a bit of an opportunity."
The theory behind using multiple opensides is obvious in the sense of controlling the all-important breakdown. But, as always, there's more than meets the eye.
In a perfect world, embracing three traditional sevens allows the All Blacks to cover more ground while pushing the pace in the final quarter when opposition, particularly in the Japanese heat, often feel the pinch.
"Each game is different," Todd said. "With conditions here hopefully they are good and the ball is in play a lot and we can play that sort of up tempo game and bring the attrition into it so that can help.
"That's always the plan but it's easier said than done. That's certainly what we're trying to achieve to play with pace and take opportunities when they present themselves but there's a lot that goes into being able to do that.
"We're still working on how to get that balance right and how best we want to play.
"At the same time it could be wet and about set piece so you've got to be versatile and be able to adapt depending on the game and how it's going."
The other side of the equation is probably more valuable.
Turnovers are difficult to gain in the modern game but, in many respects, they present the best chance to strike.
Turnovers force the opposition to switch from attack to defence in an instant, often leaving a fractured defensive line little time to scramble and plugs gaps.
Whether it's a skip ball to the edge or kick in behind, space is there to exploit if this transition phase is executed at pace.
No one is better in world rugby at striking from turnover possession than the All Blacks. Having two fetchers on the field at all times, hunting and poaching, increases the chance to create and convert these lethal opportunities.
Where others favour brawn on their bench, this is why the All Blacks may opt for speed.
It's another point of difference, another example of thinking outside the traditional rugby square.