It is already clear these two sides will be in the mix for the title and both will want to make a statement of intent.
What adds even more spice to the occasion is that Jose Mourinho and Pep Guardiola both go into their much-anticipated first meeting in English football with 100% records after winning their first three league games.
Things are going very well for them, and their new players, but this is obviously the biggest test they have faced at their new clubs so far.
All things considered, it is brilliant for the Premier League that this match is happening so early in the season.
‘Missing Aguero a massive blow for City’
While the outcome will not tell us everything about United or City, it will reveal a lot more about how they are truly shaping up.
I am really looking forward to it. I think it will be a ferocious battle and it is extremely tough to call, although I probably favour United slightly because City have striker Sergio Aguero suspended, which is a massive blow for them.
I don’t think City or Aguero had much of an argument that he did not deserve a ban for his elbow on West Ham’s Winston Reid before the international break.
It was the right decision in the end but my only concern – which was also the reason City appealed – is Aguero was able to be punished retrospectively because referee Andre Marriner did not see the incident at the time.
I do wonder, if the referee didn’t see it, what on earth was he looking at?
‘United’s height and power give them an aerial threat’
Kelechi Iheanacho, Nolito or even a rejuvenated Raheem Sterling could lead City’s attack instead of Aguero on Saturday but Guardiola has some other big decisions to make.
New goalkeeper Claudio Bravo has played in plenty of big games for Barcelona and Chile but he has hardly trained with the rest of the City squad since he joined at the end of last month.
So it would be a gamble to hand him his Premier League debut in a game this big, especially in a derby atmosphere and against a team that pose as much of an attacking threat as this United side do.
Mourinho v Guardiola head to head
Goals by minute scored
The height and power of United striker Zlatan Ibrahimovic will make Saturday a big test for City’s entire defence, not just their keeper.
As I said in my analysis on The Premier League Show on Thursday, United under Mourinho get the ball into the box far earlier and far more often than they were doing last season.
This season they have already made 53 crosses from open play, compared to 29 in the final three games of last season.
This story originally appeared on bbc.com.