This weekend told you everything you needed to know about who is in contention for the Premier League title this season in what is already shaping up to be a two-horse race.
Both Manchester clubs have the required self-belief and confidence to produce crucial victories under pressure, often coming from behind to do so — those qualities are patently lacking in the other challengers.
The effect both City and United have on the opposition is key, because there never seems any doubt that they will somehow triumph, regardless of who they are playing in the league.
There is almost a sense of inevitability about most of their games with that winning mentality always very apparent. All top sides have that grit and determination, and City and United both do in spades.
Arsenal are the opposite because they have talented players but lack belief at vital moments in matches - and do not seem to have that presence against teams such as Fulham, which they need to be beating.
There was not a moment during Arsenal's match with Fulham when it looked as though the home side would not concede imminently, and to draw 3-3 in that type of game is simply unacceptable.
Equally, Chelsea and Liverpool do not have the squads or firepower necessary to produce positive results consistently enough to mount serious title challenges.
Chelsea are going to be short on goals over the course of the season, despite the quality of the likes of Juan Mata, Eden Hazard and Oscar with Torres continuing to flounder horribly for Roberto Di Matteo's side.
It was telling for me, looking at the players introduced off the substitutes' bench: Chelsea brought on Daniel Sturridge to replace the ineffectual Torres, while City were able to introduce the prolific Edin Dzeko.
Despite the fact that City are continuing to thrive in the league, I do think that Mancini wasted the summer transfer window and did not bolster his squad as was asked of him.
It was clear to most people in football that he targeted Robin van Persie and Daniele De Rossi, but he did not have alternatives and failed to capture either player.
Worse than simply failing to improve his squad, Mancini seems to be determined to derail his side's campaign with persistent changes to the shape and strategy of his defence, in particular.
It is almost as though he is attempting to prove himself to be a master tactician with constant alterations and changes of personnel, instead of sticking to a winning formula and one that the players were very comfortable with.
The continued omission of Joleon Lescott is a prime example, with Mancini adopting the 'change for change's sake' approach. Vincent Kompany has struggled as a direct result of having that partnership removed, and it is all very unnecessary and unhelpful.
One almost gets the feeling that City are competing for the title in spite of their manager, due to the wonderful collection of stars at his disposal. That should not paper over the cracks, however, and they are suffering for his lack of direction and conviction.
I cannot believe that he seems to have forgotten what it was that won his side the title last season, and that was having a rock solid defence and creative players to provide the cutting edge in the final third.
As a former player, I can say that it played havoc with the entire team when unnecessary tinkering occurred, and I cannot fathom why he is over-thinking everything to such an extent.
It is almost as if Mancini coaches his side while they are on the field of play, and that is too late: if he has a system that he wishes to implement, he must leave all of that on the training field.
Sir Alex Ferguson gets the most out of his players and, with an inferior squad to City's, that is why United are still able to compete and to challenge with their rivals.
United have a clear identity through the way that Ferguson asks his side to set up and to approach games; City do not, and that is entirely down to Mancini.