Both teams are engaged in Champions League matches today but the focus has already been shifted to the Manchester derby at the Etihad Stadium on Sunday where Manchester City will host city rivals Manchester United.
While Manchester City will welcome Shalchtar Donetsk to the Etihad Stadium today in their Group F Champions League match, Manchester United are already in Turin today, preparing to meet Juventus who pipped them 1-0 at their backyard at Old Trafford last week.
Ironically, their Champions League matches seem insignificant to football connoisseurs who are looking forward to their epic derby at the Etihad Stadium where the host team have been rated favourites by bookmakers.
While Manchester United's defence has been under scrutiny, the real gulf between them and Manchester City is in their attacking play.
To Adam Bate of Skysport News, Manchester United's defence has become one of the key concerns among football fans this season.
With the club failing to acquire their desired targeted defenders this season, they have struggled to cope with the key contenders of the English Premier League trophy
The contrast with Manchester City is stark. But while that feels like a role reversal - the supposedly adventurous Pep Guardiola breaking defensive records, while Jose Mourinho sees his side shipping goals - it is the familiar difference in attacking cohesion between their respective teams that is still likely to be the most striking feature to pull the fans to the Etihad Stadium during the Manchester derby on Sunday.
There are many ways in which the growing gulf between the two sides is manifesting itself. And yet, it is perhaps the regular sight of City stroking the ball around with such confidence before cutting through their opponents that so grates with United supporters who long to see such obvious attacking purpose from their own team.
The bald statistics reveal much of the problem. The fact that City have scored 33 goals this season to United's 19 is a good place to start.
However, what is much more fundamental about the two teams is about style of play, as well as substance. It is not just that City scoring more goals or shooting more shots from dangerous positions.
What makes Guardiola's team so attractive to watch - and something that is an ongoing issue for Mourinho - is the way in which his team fashion openings.
Mourinho has spoken of the need to improve in the attacking phase and the difficulty of maintaining balance while doing so. Clearly, there are lots of challenges facing him and the defensive problems do need addressing.
But if there is one single aspect of United's game that highlights the difference between them and City, it is what they do when in possession.
The rivalry between Manchester United and Manchester City was forged in Victorian times - but has arguably never been more fierce than it is today.
It is worth acknowledging that this is not a new problem. City were top in all of these aforementioned metrics last season too.
United, meanwhile, were down in fifth or six for each but that neither stopped them from finishing second in the Premier League nor did it prevent them from winning the derby at the Etihad Stadium in April.
But it is a clue that the difference between the sides runs deep. It is not just there in the 19 point gap last season, and it is unlikely to go away with the signing of a centre-back or a bit more luck in front of goal.
What is at stake now is that United's attacking play is so inferior to all of their rivals - City, in particular and until that changes, the balance of power is unlikely to shift back in their favour.