In a matter of weeks, we may well have a situation that hasn't been seen in Europe for years.
Should the Manchester clubs continue their assertive start to the Europa League, the continent's secondary competition may well provide a battleground for two of its premium clubs to play out their campaigns. Depending on the circumstances, it could well alter the momentum of the English domestic season and help decide the destination of the title.
The last time anything like that happened was 1994-95. On 17 May, a Dino Baggio-driven Parma finally got the better of Juventus as they held out for a 2-1 aggregate win at the Stadio delle Alpi to seal the UEFA Cup.
It is possible, however, that Nevio Scala's provincial side overplayed their hand. Four days later at the same stadium, Juventus gained revenge as they hammered Serie A's second-placed side 4-0 to ensure Parma could no longer overtake them at the top of the table. A few weeks later, Italy's new champions added insult to inundation by also beating Parma in the Coppa Italia final.
In the end, the UEFA Cup may not have defined that Serie A season, but it did play an undeniable part in deciding it. Parma may have won a first battle, but it gave Juventus the hunger and intimate knowledge of the opposition to win the war.
The pity for the revamped Europa League now is that, in the current context of continental football, any repeat of that scenario would likely prove unique - and that's if it even actually happens with United and City. Because it used to be quite commonplace: the old UEFA Cup often set the tone and template for seasons to come.
Consider the following.
In 1973, Liverpool laid down a European marker by beating Borussia Monchengladbach in the UEFA Cup final. In 1976, they reclaimed the trophy by overcoming Brugge.
Tellingly, when Liverpool finally reached the continent's highest stage over the next two years, they had to replay both of those pairings at the exact same point in the European Cup: 1977 saw them overcome Gladbach again; 1978 saw Brugge breached by Liverpool once more... and that after Bob Paisley's side had also continued their hex over Gladbach in the semi-final.
That situation was repeated 20 years later as Juventus and Borussia Dortmund met in the 1993 UEFA Cup final before coming across each other again in the 1997 Champions League showpiece.
Liverpool also weren't the only club to lay a marker in the UEFA Cup before immediately going on to win the premier competition.
In 1982, Hamburg reached the final 12 months before beating Juventus in the European Cup final. Juventus, meanwhile, really went from strength to strength after that 1995 defeat to Parma. The following May, they were champions of Europe.
In the modern era, FC Porto are the only team to repeat that feat, and even then it felt like an anomaly caused by Jose Mourinho's alchemy rather than anything to do with the state of the competitions.
It seems some time since the secondary competition saw such first-class football. Of course, even throughout all of those earlier years, the European Cup remained the continent's most prestigious tournament but, given that context, it may not have always necessarily decided the outright best team.
In many ways, the UEFA Cup was a better barometer for the state of European football. For a start, given that there were more places, it had many more high-quality teams. Secondly, a greater number of the UEFA Cup's sides tended to be on the rise rather than past their best. There are, after all, numerous cases of teams claiming an isolated domestic title before falling away - most notably European Cup finalists Fiorentina (1957), Atletico Madrid (1974), Aston Villa (1982), Roma (1984) and Sampdoria (1992).
A perfect example was the 1974-75 season in the Bundesliga. Bloated by four years of continued success, a complacent Bayern Munich were under a new manager but arguably over the hill as they slipped to tenth in the domestic league. They just about eked through six European Cup games against FC Magdeburg, Ararat Yerevan and St Etienne before then claiming a hugely fortunate win over Leeds United in the final.
Throughout that same season, meanwhile, Borussia Monchengladbach were blazing a trail. Playing scintillating football under Udo Lattek, they secured the first of three Bundesligas in a row before - you've guessed it - winning the 1975 UEFA Cup by thrashing FC Twente 5-1 away from home in the second leg. The coming years would belong to Gladbach and Liverpool rather than Bayern.
Likewise, if you look at the modern Champions League through the prism of the past's rules, many of its great teams would suddenly seem a little less grand. Most notably, neither Manchester United in 1999 nor Barcelona in 2009 would have claimed true trebles since their failure to win the domestic leagues in the previous seasons would have prohibited entry. Instead, they would have had to replicate that Gladbach team in 1975, Feyenoord 1974, Liverpool 1976, Juventus 1977 and Real Madrid 1986 by placing the UEFA Cup alongside their league trophies.
In all, since the initial expansion in 1997, six of the Champions League's 14 winners would not have qualified under the old rules. A majority of eight of that 14, however, did at least prove their worthiness by winning their domestic title in the same season they lifted the Champions League.
But that does raise a further question about the current make-up of Europe's competitions. The traditional view is that they should return to the traditional versions: with the Champions League being solely for champions and the Europa League being for everyone else.
But if the Champions League really is an attempt to decide the best team in Europe then perhaps it is also for the best that it include more top sides, that it continue to provide the barometer that the UEFA Cup used to. The Copa Libertadores, after all, never got so hung up on just siphoning off the previous season's champions.
Perhaps the one downside to the current Champions League, though, is that it goes too far. Removing fourth-placed teams, for example, would enhance the exclusivity of the top competition while also increasing the prestige of the Europa League. On that ground, too, maybe it's not such a bad idea that Champions League sides are parachuted in.
After all, one of the reasons that the UEFA Cup was such a high-end competition for most of its history was because every team recognised the prestige and standard of the field.
Along those lines, should the two Manchester clubs continue their present course, it might do more than replicate a seemingly forgotten scenario; it might restore the Europa League's sheen.
• Miguel Delaney is a freelance European football writer and owner of Football Pantheon.