Near the end of Hail, Caesar! the Coen Brothers' movie about movies, the director shouts in the ear of leading man Baird Whitlock.

Whitlock, a Roman general, is supposed to be having a moment of epiphany as he stares at Christ on the cross and the director urges him to convey a sense of wonder.

'Squint against the grandeur,' he says.

Pep Guardiola barks out some orders as his Manchester City side beat rivals United

That is what we came to do at Old Trafford on Saturday. To be blinded by the light.

To gaze at the lightning that crackled and fizzed when Jose Mourinho collided again with Pep Guardiola.

To wonder at this meeting of the Premier League's two behemoths who are both hell bent on domination and spending to prove it.

And we were not disappointed.

What a game it was. It will go down as one of the seminal afternoons in the history of the Premier League. What a feast.

A feast of energy and skill, of technique and commitment. A move towards a more technical style of play, with Guardiola as the pathfinder.

Guardiola has already stamped his mark on City by giving them the identity they lacked

Manchester City's performance in the first 40 minutes in particular gave this occasion the feel of a new dawn for domestic English football.

It was dazzling. There is no other word for it and, yes, amid the relentless excitement, we squinted against the grandeur.

As for Caesar, well, it has to be Guardiola. After the phoney war of the opening three games, this was his proper English baptism and what his team gave us in that first half justified all the hype and all the love that is lavished upon the new City manager when people talk about him as a kind of saviour of the beautiful game.

It felt in those first 40 minutes as though City were redefining English football.

Watching them toy with United, watching them make United chase shadows and give the ball away repeatedly, watching their comfort in possession, watching them pass, pass, pass — it felt for all the world as if we were watching one of the great continental sides teaching one of our teams a harsh lesson.

We have seen it plenty of times before. Barcelona or Real Madrid or Juventus humiliating one of our sides with their technique and making an English club side look lumpen and clumsy.

Guardiola celebrates with his City players after their victory at the home of United

Except this was not Barcelona or Real Madrid. This was City. And it was glorious to watch.

For those 40 minutes, Guardiola was intent on exploding as a myth the contention that the English game has to be all about the hurly-burly and that cerebral teams will surely perish.

Guardiola did something extraordinary here. He fought against the nature of English football and he won.

Not that we needed it, but this was the final proof that Lionel Messi could indeed have done it on a wet Wednesday night in Stoke.

At least, he could if he were playing in a Guardiola team.

The City manager showed what can be achieved with conviction and ambition. It whetted the appetite for what lies ahead.

City were hugely impressive against United, particularly during the first 40 minutes or so

United were humbled by that part of City's display. For most of the first half, the gap between the two teams yawned like a chasm.

Some of United's play looked prehistoric. It looked slow and clumsy and ponderous.

United looked like a great big blunt instrument.

On the touchline, Guardiola was a ball of energy, beckoning and gesticulating wildly in the need for control.

If Claudio Bravo, City's debutant goalkeeper, had not let United back into the game a few minutes before half-time by gifting a goal to Zlatan Ibrahimovic when City were already 2-0 ahead through goals from man-of-the-match Kevin De Bruyne and Kelechi Iheanacho, the scoreline might have become an embarrassment for Mourinho and United.

As it was, Bravo's mistake and his increasingly eccentric performance drained City of confidence at the end of the first period and for 20 minutes after the interval.

Guardiola watched on as City came out on top with Kevin De Bruyne scoring their first goal

It was a tough debut. His selection, especially for an occasion like this, was an error but it also served to demonstrate Guardiola's determination to do it his way.

And it was not all bad news for United. If a couple of decisions had gone their way, they might even have rescued a draw.

But Mourinho made mistakes by picking Henrikh Mkhitaryan and Jesse Lingard from the start and United paid dearly.

By the time Mourinho corrected the situation at half-time, substituting both men, it was too late.

So the laurels go to Guardiola. And the optimism now resides in the blue half of Manchester.

Because Guardiola did something else on Saturday. For the first time since their takeover by Sheik Mansour and the Abu Dhabi United Group in 2008, City have a real identity.

Victory for Guardiola meant he came out on top in his rivalry with United boss Jose Mourinho

They have something to define them apart from spending a lot of money.

That may be the most valuable thing Guardiola brings to City. Until now, no one really knew what they stood for on the pitch.

The pragmatism of Roberto Mancini was not particularly glamorous and even though Manuel Pellegrini's intentions were good, City's inconsistency made it hard to gauge progress.

The way they played at Old Trafford, though, was different. They stand for something now. They stand for playing football the right way.

They stand for trying to do the right thing on the football pitch. They stand for making even seasoned observers purr with pleasure at the spectacle unfolding in front of them.

For all the money City have spent, that is priceless. For all the work of their marketing men, nothing will match the benefits of this brand if it continues to succeed as it did at the home of their greatest rivals.

City have four wins from four games and if Guardiola has had this effect on them, it is tantalising to think how much they may yet improve.

This was the dream of the City hierarchy in the years they spent trying to hire him: that the magic of Guardiola would rub off on them.

That they would become a beacon of beautiful football in the way that the Barcelona side he built have been for so long.