Since Asian football's premier club competition entered its AFC Champions League era in 2002-03, no two teams from the same country have ever faced off in the final.
Even teams from the same region meeting in the last game of the season has not happened in recent times.
This was, quite simply, impossible given the format of the tournament largely separated the East and West regions until the decider.
The only precedents were all-South Korean finals in the Asian Club Championship era, where Pohang Steelers defeat Cheonan Ilhwa Chunma (now Seongnam FC) 2-1 in 1996-97, while Suwon Samsung Bluewings saw off Anyang LG Cheetahs (now FC Seoul) on penalties in 2001-02.
But with the introduction of the centralised ACL finals since last season, which now sees East and West collide from the quarterfinals, the scenario of local rivals facing off on the continent's biggest stage is now possible once more.
For all the hype surrounding their meteoric rise over the past few years, even the Saudi Pro League failed to deliver an all-Saudi Arabian finale in last season's ACL Elite -- despite having three teams in the final four.
Japan's Kawasaki Frontale would crash the party, producing a fine display to defeat Cristiano Ronaldo's Al Nassr in the semifinals before ultimately falling to Al Ahli, who claimed a first continental crown in their history.
A similar prospect remains on the cards this season but, this time, it is an all-Japan final that could eventuate -- with J1 League outfits Vissel Kobe and Machida Zelvia both into the semifinals and, more importantly, on opposite ends of the draw.
Even just getting to the final would be unchartered territory for either, with the semis being the furthest Vissel have previously reached -- back in 2020 -- while Machida have done remarkably well to get this far in their competition debut.
Both certainly were made to work for their places in the last four.
On Thursday, Vissel looked dead and buried against Qatar's Al Sadd as they were found themselves 3-1 down -- and were still headed for the exit door until Yoshinori Muto's dramatic 93rd-minute equaliser took the game to extra time and then penalties, where they prevailed 5-4 in the shootout.
It prompted Vissel coach Michael Skibbe -- who only took charge at the start of the year -- to hail the never-say-die attitude he believes is synonymous with Japanese teams, saying: "It is the mentality of Japanese teams to never give up.
"We tried to score until the last second and, even in the last second, we [did] it."
Meanwhile, Machida did not need over 120 minutes to see off their opponents but they still were made to work for an impressive 1-0 victory over a star-studded Al Ittihad outfit the following evening.
Tete Yengi's deflected strike in the 31st minute proved to be the only goal of the game, but Machida were twice rescued by goalkeeper Kosei Tani's woodwork -- while Al Ittihad also had a late equaliser ruled out by VAR.
"This was the first stage [of the finals] for us and it was a very big one," said Machida coach Go Kuroda, who already has been vocal about their ambition to go all the way even if it may be their first foray in continental football.
"It was a really, really tough game but I'm so pleased all the players are united and kept a clean sheet. I'm so happy for them."
Both teams will certainly be aware that here is more hard work in front of them if they are to reach Saturday's final.
Vissel are first up on Monday against defending champions Al Ahli, who deserve plenty of credit for seeing off Johor Darul Ta'zim in the quarters -- coming from behind to win 2-1 despite playing with a numerical deficit from the 37th minute.
Machida are in action the following evening and will take on a Shabab Al Ahli side that were issued a real challenge by Buriram United on Saturday but still managed to prevail 3-2 in extra-time.
Intriguingly, Machida's continental debut was sealed by defeating Vissel in last year's Emperor's Cup final -- which was also their first major piece of silverware.
Should the two Japanese teams indeed advance to the final, Machida will be gunning for a repeat result while Vissel will surely have revenge on their minds.
First, they will have to get past their respective semis.
Given the ACL Elite finals are held in Jeddah, the dream final for the locals was always going to be a clash between Al Ahli and Al Ittihad.
That can no longer be the case following Al Ittihad's exit.
But over 5,000 miles away, Japanese football can still dream of a Vissel-Machida decider.