Manchester United are arguably the biggest obstacle standing between Manchester City and a domestic treble of Premier League, FA Cup and League Cup.
United, of course, are the only English team to have won what we have come to think of as the ultimate Treble - Premier League, FA Cup and Champions League.
Victory at Old Trafford on Wednesday would take Pep Guardiola's side a huge step towards their own unique feat, a trio of trophies no English team has won before in the same season.
So as the two Manchester clubs go head to head in a game of such magnitude, it seems like the perfect time to compare United 1999 and City 2019, and consider which players might make it into a combined XI.
Goalkeeping: Creator or destroyer?
Nowhere is it more obvious that football has changed between the 1990s and now than with goalkeeping.
Peter Schmeichel's first Premier League title with Manchester United in 1993 came a year after the dreary safety valve that was the picked-up backpass was outlawed, and just six-and-a-half years after his son Kasper was born.
Now, keepers pass the ball like Giuseppe Giannini and Kasper is a man in his 30s who has a Premier League winner's medal of his own. Life moves on.
Even so, Peter Schmeichel or Ederson? The United man had a pass completion rate of only 48% in 1998-99, but had to make (poetically) 99 saves in the Premier League as United edged the title from Arsenal.
This season, Ederson has stroked 71% of his passes to a team-mate but has only had to make 54 saves as City's dominance of the ball, in the form of an opposition-numbing average possession rate of 68%, makes him as much a creator as a destroyer of strikers' dreams. The Brazilian has provided more assists for Premier League goals than United's Romelu Lukaku has this season.
It boils down to this: do you want to see a goalkeeper making fingertip saves and occasionally going up for late corners, or do you want an 11th outfielder selling outrageous dummies to opponents hurtling towards them? There's no right answer, it's just a question of aesthetics.
Defending: Forget what you thought you knew
Manchester City will have to concede 16 goals in their final four league games this season if they are to finish with a defensive record inferior to Manchester United's in 1998-99.
That famous defence of Gary Neville, Jaap Stam, Denis Irwin and one of Ronny Johnsen, Henning Berg, Wes Brown or (occasionally) David May actually conceded three at Arsenal, three at Sheffield Wednesday and three at home to Middlesbrough.
The current City team have conceded three in a Premier League game just once this season, and only three times since January 2017.
So, the United defence you thought was all about defending is worse than the City defence you thought was all about attacking. But wait: Neville, Stam, Irwin, Berg and Phil Neville contributed 10 assists between them in 1998-99.
Benjamin Mendy (who flourished briefly in the autumn) aside, City's defenders do not generally offer the same raw output. Their job is incessant circulation but it was the United defenders who could make the opposition backline's blood run cold.
Midfield: Icons and record breakers
Name a more iconic midfield than David Beckham, Roy Keane, Paul Scholes and Ryan Giggs.
In the Premier League alone in 1998-99, those four contributed 37 goals and assists between them, plus another five from Pele's favourite, Nicky Butt.
And before you say "that was a settled team, the modern game is riddled with rotation", bear in mind that the "classic" United Treble XI of Schmeichel, Gary Neville, Irwin, Johnsen, Stam, Keane, Scholes, Beckham, Giggs, Yorke and Cole only ever started together in one game, and that in a stadium which no longer even exists - Coventry's Highfield Road in February 1999.
But contemporary Manchester City's midfield certainly does exist and they too have players with numbers worthy of celebration. David Silva has 21 more assists than any other Premier League footballer in the 2010s, Kevin de Bruyne has the best minutes-per-assist rate (197.0) in Premier League history, followed in second place by Leroy Sane (212.1).
Then again, David Beckham has scored six more direct free-kicks (18) than any player in Premier League history and three times as many as Burnley.
We've all got stories.
Patrick Vieira getting a coaching job in Manchester before Roy Keane would have confused people in the early 2000s and goes to prove that the future brings many unexpected outcomes.
Perhaps Phil Foden may turn out to be the manager to finally bring the title back to Old Trafford in 20 years, but in the meantime we can agree that there really isn't much between the midfields of 1999 and 2019.
Attack: De Bruyne to Silva to Yorke to Cole… GOAL!
In the late 1990s, Manchester United had four first-team-quality strikers, back when rotation was called strength in depth.
City rely more heavily on the likes of Raheem Sterling and Sergio Aguero with the former becoming, in March, the first England player to score a hat-trick for both club and country in the same month since 1999.
The latter, meanwhile, has the best minutes-per-goal rate in Premier League history (108.0), the joint highest number of hat-tricks in the league's history (11) and needs one more goal this season to join Thierry Henry as the only players to score 20 or more goals in five successive seasons.
Even so, how would Guardiola deploy Dwight Yorke, Andy Cole, Teddy Sheringham and the man he'll face on Wednesday, Ole Gunnar Solskjaer?
Cole often feels like the unfairly forgotten man in the Premier League goal-total annals, his haul of 187 - with only one penalty - putting him well ahead of the other players to reach treble figures with one or zero spot-kicks to their name (Les Ferdinand, Emile Heskey, Peter Crouch and Paul Scholes).
Yorke, meanwhile, has the unlikely honour of being the only player to score eight or more headed goals in multiple Premier League seasons.
We started this whole process by noting the vast difference between Schmeichel and Ederson, but at the other end of the pitch it feels much more interchangeable.
If Aguero had played in United red as the 20th century came to an end, he would have racked up a lot of goals. Similarly, the interplay between Yorke and Cole would not look out of place on the scribbled pages of a Pep Guardiola tactics sketchbook.
Which team is better? One won the Treble, the other is five games from their own version of it.
Back in 1998-99, City were scrapping their way out of the third tier of English football, and had not defeated their rivals for 10 years. Things aren't quite that bad yet at Old Trafford but it's a handy reminder that football is reliably cyclical. The only currency that lasts is good players.