Rugby's world order has been shaken. Again.
Four years after they stunned the rugby world in the English seaside town of Brighton, Japan on Saturday evening repeated the dose. This time at home.
It was an inspired performance from the Brave Blossoms on Saturday afternoon in Shizuoka, where they were cheered on by a raucous home crowd, as they came from behind to defeat Ireland 19-12 to notch another famous win to go with their upset of South Africa in 2015.
Japan's victory means the hosts could now end up topping Pool A, which would see them avoid a potential quarterfinal with the All Blacks and instead earn a likely date with (who else?) South Africa in the quarterfinals. Suddenly the semifinals are a possibility and given how they fought back in Shizuoka, only a fool would say that achievement is beyond them.
While the Rugby World Cup's first foray into Asia has been embraced by the people of Japan, the Brave Blossoms' victory on Saturday afternoon will take things to another level.
It also validated coach Jamie Joseph's pre-tournament plan that saw many of Japan's best players sit out the majority of Super Rugby and instead focus purely on the World Cup.
"We obviously had plans and we've been training for a long time, but we've been thinking about this game for a long time," Joseph said. "Obviously Ireland were only thinking about it for the last six or seven days but for us it's been a great performance.
"I was trying to be careful before the game, I guess you don't want to come across as arrogant. We obviously had a lot of belief in our game plan, in what we wanted to do, and our group knew how good Ireland were, how strong they were.
"And I've got to say credit to my coaching team; set-piece, we were able to thwart their set-piece; we've got a great scrum coach. And Tony Brown built a great attack plan; we all worked together."
Two first-half tries from Ireland looked to have the world's No. 2-ranked side on their way to victory, but Japan slowly reeled in the early 12-3 margin through the boot of fly-half Yu Tamura, and then took the lead themselves when replacement Kenki Fukuoka finished off a sweeping try that will be remembered with the same fondness as Karne Hesketh's match winner from four years ago.
But when Hesketh's five-pointer had come after the final siren, Fukuoka's effort arrived on 59 minutes, which meant Japan still had more than a quarter of the match to defend in Shizuoka.
Their fitness tested in the sweaty home conditions, Japan never wilted as Ireland pressed to regain the lead; the hosts still scrambling for tackles and rushing to breakdowns with the same venom they had in the game's opening exchanges.
The gravity of this win cannot be understated. Ireland were, up until Sunday, the No. 1-ranked team in rugby and only lost that due to the All Blacks' victory over the Springboks one night earlier.
The Irish, granted, were without reigning World Rugby Player of the Year and star fly-half Johnny Sexton, but they were still thought to have possessed enough class to defeat Japan.
That was clearly not the case, and even coach Joe Schmidt was forced to concede postmatch that, at 12-3 ahead, Ireland had "stopped playing."
Japan had targeted a quarterfinal finish at this tournament from the moment they were denied a similar result four years ago, when they became the first team to win three pool games and miss the knockout phase, but surely not even in their wildest dreams did they imagine it coming with a win over Ireland.
They still have games to negotiate against Samoa and, in the closing match of the pool stage, Scotland, but this victory has put them on the verge of a momentous achievement in Japanese sport and the game of rugby on the whole.
The Rugby World Cup is alive and kicking and World Rugby has Japan to thank. Again.