Manchester United have the chance to close the gap on their City rivals to just one point and continue their revival under Ten Hag with a win at Old Trafford this weekend.
It is a scenario that would have seemed impossible a few months ago, with United fans fearing the worst after a disastrous start to the campaign that saw a 2-1 loss at home to Brighton followed up by a humiliating 4-0 collapse at Brentford.
Despite an uptick in form, it wasn’t long before United found themselves 6-1 down against Man City with both Erling Haaland and Phil Foden rubbing salt in the wound by netting hat-tricks in Guardiola’s 500th game in charge.
But time is a great healer.
Eight consecutive wins on the bounce have seen the Red Devils steadily climb the table and reach the latter stages of the Carabao Cup and FA Cup.
These wins might have come against lowly opposition - including Charlton, Nottingham Forest, Wolves, Bournemouth and Everton - but there is a growing sense of optimism at Old Trafford that life is getting back to normal under Ten Hag after the disastrous spells of Ralf Rangnick and Ole Gunnar Solskjær.
Twelve months ago Ten Hag managed his 100th win in just 128 games for Ajax, a club he guided to three league titles and steered to the semi-finals of the Champions League.
But even the Dutchman would admit that he might not have reached such heady heights had it not been for Guardiola's influence.
The 52-year-old makes no secret that Guardiola was the reason why, in 2013, he decided to step down as manager of Go Ahead Eagles after just one season - having guided them to promotion to the Eredivisie for the first time in 17 years - to oversee Bayern Munich's second team.
The demotion was a bold move that would pay dividends. Returning from a season-long career break, a rejuvenated Guardiola managed Bayern's first team on an adjacent pitch. Ten Hag described working under the Spaniard as "like winning the lottery".
Guardiola's meticulous attention to detail and no-nonsense approach saw him claim 14 trophies across six competitions and that winning mentality rubbed off on Ten Hag.
The Dutchman led the second team to the Regionalliga Bayern title in 2013/14 - the same year Guardiola won the first of three consecutive Bundesliga titles for the senior team - and used the same approach at Manchester United after he was appointed their manager in April 2022.
"He worked with Pep at Bayern Munich and took his philosophy too," Man Utd assistant manager Steve McClaren told the Daily Telegraph.
"They called him 'Mini Pep' out there, tactically he’s outstanding. Erik is very disciplined."
Ten Hag's ruthlessness has already come to the fore this season with the high-profile departure of Cristiano Ronaldo and the decision to bench Marcus Rashford and captain Harry Maguire, drawing similarities to the way Guardiola dropped England goalkeeper Joe Hart at City and dispatched Deco and Ronaldinho in his time at Barcelona.
In doing so, results have improved dramatically. After a tumultuous start, United are behind third-placed Newcastle on goal difference, through to the semi-final of the Carabao Cup and host Reading in the FA Cup fourth round with Barcelona to come in the Europa League play-off.
Not even Guardiola won a trophy in his first season at the Etihad, leading City to a third-place finish in the league and semi-final of the FA Cup after being dumped out of the Champions League in the last 16.
But is it fair to compare the success of the two managers given the relative state of the two clubs?
Man City was a club waiting for Guardiola to make his own and in the six years following has broken multiple records on their way to winning eight major trophies, with the Champions League the only notable absentee from a glittering trophy cabinet.
By contrast, it could take several years for Ten Hag to rebuild decades of underfunding and poor management at Old Trafford.
But at least the Glazers, in most likely their final months of strained ownership, have given their full backing to the Dutchman allowing him to splash a club record £229m during the last transfer window in the hope of ending a rot that has seen the club win only one trophy since 2017.
But if it all falls apart at United, could Ten Hag do the unthinkable, step into Guardiola’s shoes when the time comes at City, and emulate his achievements there?
"Are you asking me if Erik Ten Hag could be here?" Guardiola asked reporters last year. "Definitely."
"For the way he approaches the game? Definitely, definitely."
