They are the two managers who have redefined what greatness looks like in the Premier League.
But Jurgen Klopp’s next battle with Pep Guardiola could just be the most intriguing yet.
After losing out by the most wafer thin of margins in 2019 when a total of 97 points was not enough to be crowned champions, Klopp’s Liverpool responded emphatically.
The Reds, somehow, bettered their tally of the previous year when they won the Premier League title with a record seven games to spare before ending with 99 points.
Guardiola’s City, however, would then offer their riposte as they became the first club to truly figure out what some have labelled ‘pandemic football’.
It was enough to crown them champions for the third season in four and it is not over yet for City as they go in search of the first Champions League success this weekend against Chelsea in Lisbon.
“The people who believe we are contenders because of just money, they have [made] a f****** big, huge mistake,” snorted Guardiola as City celebrated their league title on Sunday at the Etihad.
A third-place finish was all Klopp’s side could muster as they finished their season some 17 points behind Guardiola’s men.
Such was the paucity of Liverpool’s defence of their first league title in 30 years that some questioned whether they were the worst defending champions of the Premier League era.
That hyperbole, while boorishly predictable, does not hold up to scrutiny given City’s own defence in 2020 was surrendered by 18 points.
However it is sliced, though, there can be little denying that Liverpool, when the elation of their surprise third-place finish subsides, will be hurt by how events of last season turned out.
The inquests into where and when it went wrong are likely to be swift when the squad reconvene at the AXA Centre in July.
A crippling injury crisis that forced Klopp to utilise 20 different centre-back pairings across the campaign was the root cause.
Being without Virgil van Dijk, Joe Gomez and Joel Matip for the majority of the season would hurt any squad.
The lengthy absences of players like Diogo Jota, Jordan Henderson and Thiago Alcantara were not conducive to a title charge, either.
But that mitigation cannot shield Liverpool and Klopp entirely.
They will be acutely aware that performances, particularly for the first three months of 2021, were far below what has become the requisite standard at Anfield.
It is a standard they are trying to reach once again next term and the recent signs are positive on that front.
A stirring finish that saw Liverpool win eight and draw two of their final 10 games was enough to end a forgettable season on a high.
Klopp and his staff will know that more lofty ambitions will be demanded in August and the Reds boss will have ample reason to believe they can be met.
Virgil van Dijk, Joe Gomez and Joel Matip, Liverpool hope, will be fit for pre-season action, while the move for Ibrahima Konate hints at a willingness to get the big business concluded early.
The Reds are pushing on with their efforts to sign the RB Leipzig defender for around £40million and significant movement is expected on that when he returns from European Championship duty with France’s Under-21 side next month.
Those who may feel that City’s dominance this season leaves Liverpool with an uphill battle only need to take a cursory glance at recent history, however.
Over the last three seasons, both clubs have amassed the exact same number of Premier League points.
After picking 99 to add to their 97 in 2019, Liverpool eventually amassed 69 this campaign to round that total up to 265.
For their part, City reached that same figure by securing 81 and 86 after their 98 two years ago.
These, then, are the standards that have now been set. Guardiola and City know it, so too do Klopp and Liverpool.
But while the City boss was strong in his rebuttal over spending power on Sunday, Guardiola’s insistence that it is not just about money suggests he knows Klopp’s Liverpool will respond again.
The Premier League’s most new-age of rivalries is set for its fourth round next season.