At Cristiano Ronaldo's introductory press conference at Old Trafford, more than nine years ago, there was none of the preening or ostentatious expressions of boredom he favoured in later years, instead he was every inch the awkward teenager. Someone asked him who his favourite player was and he replied that it was Thierry Henry. Sir Alex Ferguson groaned. At that time Manchester United's rivalry with Arsenal and Ferguson's animosity with Arsène Wenger were at their height.

Yet on the pitch what was immediately obvious about Ronaldo, apart from the raw natural talent, was an ambivalence to the opinions of more experienced team-mates that is rare in a young player. If he wanted to do half-a-dozen stepovers then he was damn well going to do them and sod what Ryan Giggs or Ruud Van Nistelrooy thought.

It took a few years for the all-conquering Ronaldo to emerge. In his recently serialised book, Wayne Rooney observed that Ronaldo had come back "muscly and beefed up" in the summer of 2006, "like he'd been on the weights all summer". The rest is history.

The Ronaldo whom Manchester City face tomorrow in the Champions League is 27 and much more experienced, but still a curious character. That teenage single-mindedness has hardened further. There scarcely seems a player more set upon doing his own thing. High-maintenance? You bet he is. On the flip side he has scored 151 goals in 150 games for Real Madrid (including the disputed free-kick), which isn't bad.

It is an indicator of just how delicate Ronaldo's ego can be that he made it clear he was displeased that the Real president, Florentino Perez, did not accompany him to Monte Carlo for last month's Uefa "best player in Europe" presentation. The two other finalists, Lionel Messi and Andres Iniesta, had Sandro Rosell, the Barcelona president with them; Ronaldo got Pedro Lopez, the club's "third vice-president". Do such things really matter? Apparently they do.

A brilliant athlete with extraordinary skill, Ronaldo will always have that touch of the Little Lord Fauntleroys about him. His latest disaffection, his so-called sadness, has at its root the simple matter of money. Ronaldo wants a new contract worth €13m (£10.5m) net a year, which under Spain's new tax laws will cost Madrid around double, grossed up.

When Ronaldo was signed in 2009 his contract was agreed under the terms of the tax break for foreign nationals in place at the time, which obliged him to pay just 24.75 per cent income tax. A new contract would mean Ronaldo was no longer eligible for that rate and would pay 52 per cent. His net demand has been interpreted as the reason why Madrid are delaying on the contract.

Is he worth it? If we suspend reality for a moment and remember that we are talking about football, not the real world, then consider that Samuel Eto'o, Zlatan Ibrahimovic, Rooney, Yaya Touré, Sergio Aguero, Didier Drogba, Fernando Torres, Dario Conca (an Argentine who plays for Guangzhou in China) and Lionel Messi were all listed in a recent Marca newspaper study as earning more than Ronaldo.

It is difficult to measure, for instance, the extent of what Touré does for Manchester City against Ronaldo's contribution for Madrid but, Messi aside, you could make a strong case for Ronaldo eclipsing every other player on that list.

No one would claim that these lists are entirely accurate. Nevertheless, Ronaldo has gone more than three years without a new contract which, for a player of his status, is unusual. At United he signed two upgrades on his original deal in six years. In the meantime, the salaries for elite players at the best clubs rise more steeply than London house prices.

The second question is whether a salary of €13m net is morally sustainable in a country that is suffering 53 per cent unemployment among 16 to 24-year-olds. Ronaldo has never projected the image of a man who is too concerned about the world beyond the perimeter walls of his luxury home. He is a kid from a poor family in Madeira who plays football and dates models. That seems to be pretty much it.

Nevertheless, Ronaldo is not responsible for Spain's financial woes. He may also wish to point out that Alfredo Sáenz, the chief executive of Banco Santander, currently earns more despite presiding over a profit slump that resulted from a £538m compensation payout for mis-selling.

Real Madrid, on the other hand, are in fine fettle. They are the current league champions and last season reported revenues of €514m, making them the first club to break through the €500m barrier. Their debt is down €45m to €127m and their assets, needless to say, are extensive.

Tomorrow's game at the Bernabeu is a treat, encompassing the rivalry between Jose Mourinho and Roberto Mancini: a clash between Europe's old money and its new money and some of the biggest names in the game. But everyone knows that the real headline act, the man to whom the television cameras will be drawn time and again, will be Ronaldo.

He may be copping the blame for Madrid's current poor form, including Saturday's defeat to Seville, but he is still the star of the show, even a show as big as tomorrow night, and the star – as Madrid are discovering – has to be paid. He has earned it.

At some point someone will point out that the €30m gross he wants every year could be better spent elsewhere – hospitals, schools, paying down the national debt. No one could dispute that. But is that where Madrid would channel any savings on Ronaldo's salary? Would they heck.

Yes, all that money on one man in a country where the national debt is now 76 per cent of the nation's GDP is obscene. Yes, Ronaldo can be a bit of a prat. Fortunately for him, however, he is the most crucial employee in a Spanish business that is booming. It is easy to demonise a footballer, especially one who can occasionally lack self-awareness, for simply asking for what he believes he is worth.

In the two summers that he clearly wanted to leave United, Ronaldo talked about joining Madrid as the fulfilment of a boyhood dream. Fair enough but, in his current stand-off, we have learnt that while Madrid may have a hold on Ronaldo's imagination, it is his determination to be paid the market rate that steers the boat.