According to his inner circle, there was only one team Neymar had his heart set on playing for: Barcelona. Coached by Pep Guardiola and led on the field by Lionel Messi, the Catalan club had beaten Manchester United 3-1 at Wembley Stadium in May 2011 taking its third Champions League title in five years, cementing a period of dominance not seen for years. Alex Ferguson, the losing side's manager, said it was the best team he had faced in his 40-year career. Of Andrés Iniesta and Xavi Hernández, the axis of the team in midfield, Ferguson said they passed the ball so fast and accurately it made your head spin. After his team had lost 4-1 at Barcelona the previous season, Arsenal coach Arsène Wenger said Messi's magnetic control of the ball was as though he was a player in a PlayStation video game. As the plaudits lined up, Neymar was sure he wanted to be part of this football dynasty.

Barcelona president Sandro Rosell, who had worked in Brazil as a Nike marketing executive, asked Brazilian André Cury to lead negotiations with Neymar and his father. The pitch was a simple one: “Do you want to play for the best team in the world?” Real Madrid had delivered messages to Neymar from Cristiano Ronaldo and Jose Mourinho, but the introverted Lionel Messi never dropped a line or sent a message encouraging the teenager to join him. Perhaps it wasn't necessary. Neymar was only 19 and had only recently moved out of the one-bedroom family home when he secretly agreed to join Barcelona. On 15 November 2011, Neymar signed a deal pledging to join Barcelona in 2015, and in return the club would pay him an initial €10 million and a further €30 million when he moved. Three days later, Neymar's parents formed a company called N&N Consultoria Esportiva e Empresarial to receive the first payment. Ten million euros were wired into its bank account in São Paulo.

The pact wasn't made public and not even Santos knew about it. Eight months later, Barcelona buried the terms of the deal on page 178 of its financial accounts, saying it had made a down payment on a future purchase without giving any more details or mentioning Neymar's name. Santos president Luis Álvaro de Oliveira said that the first he knew of the agreement was when O Globo published the details two years later.

Having signed the secret deal with Barcelona, Neymar's father continued to exert pressure over Santos by requesting it shorten his son's contract by one year to 2013. Barcelona wanted to bring forward the deal, because Real Madrid was still pushing aggressively to sign Neymar. Real was offering him a higher salary and offered to pay the €40 million he would be liable to pay Barcelona for rescinding their deal. Barcelona reminded Neymar that he would have to share half of his pay from new sponsorship contracts with Real Madrid.

Barcelona won the tussle and negotiated what appeared to be a very modest €17 million transfer fee with Santos. It was a personal victory for the Barcelona president Sandro Rosell. The handsome son of a former club director, he was a member of the Catalan establishment and was reported to have a fortune of €250 million that included petrol stations and property. A decade earlier, Rosell had boasted how as vice-president he had persuaded another Brazilian star, Ronaldinho, to join Barcelona ahead of Manchester United. Beating Real Madrid to Neymar was an even bigger coup. Clean-shaven and dressed in a dark-blue suit and check tie, Rosell hugged Neymar at the signing ceremony and chatted amiably to him in fluent Portuguese. But the taste of success would not last long for the president. At about the same time, Rosell was making an enemy among the team's fans.

Jordi Cases, a pharmacist in his 40s from a town outside Barcelona called Olesa de Montserrat, had a season seat in the cheap third tier at the Camp Nou stadium that cost a few hundred euros a year. Cases had become incensed by a decision by Rosell to sign a €30 million-a-year sponsorship deal with Qatar to replace children's charity Unicef. Prior to the Unicef deal, the club had never had a brand name on it shirts. He felt that Rosell and his board were betraying the motto of being “més que un club” (Catalan for “more than a club”). The words were painted onto the seats at the 98,000-seat Camp Nou stadium.

Presented by Rosell as a way for Barcelona to stay competitive in the Champions League against superpowers such as Bayern Munich and Manchester United, the Qatar sponsorship was approved by just 697 Barcelona members with voting rights at the previous annual general meeting. Cases said the sponsorship was such a significant development that all of the members should be consulted. He and some friends set up a pressure group to try and force a new ballot of all 170,000 members. The motion failed to get enough signatures.

Barcelona is in theory controlled by its members: it's they who elect the president and the board every year. But Cases was irked by the lack of say the members had once the election was over. After failing to make headway with the decision to put Qatar's name on the team shirts, he turned his attention to page 178 of the club's financial report that mentioned a €10 million down payment on a €40 million accord. Was this to Neymar? He wrote to Rosell and the board seeking more details. They ignored him.

In December, Cases faxed a complaint to Spain's National Court in Madrid asking it to investigate whether Rosell had misapplied funds to make the payment. He said that he wasn't accusing the president of a crime, he just wanted to know how the club was spending money on behalf of members.

The board responded to Cases this time. Rosell called the complaint “reckless” and his general secretary, Tony Freixa, wrote a letter in Catalan on Christmas Eve to the family pharmacy saying the club could seek damages from him if confidential details about Neymar's contract were made public. “As you can imagine, the size of the damages would be very high,” Freixa wrote.

Cases was unbowed – defiantly, he would add the words “reckless and imprudent” to his Whatsapp profile. When, after the Christmas break, judge Pablo Ruz agreed to investigate, Cases realized he had triggered a scandal. Rosell immediately quit as president, although he continued to deny wrongdoing. He said he was stepping down to stop the fallout affecting the club.

After receiving permission from Neymar's family to speak in public, Barcelona called a press conference. With PowerPoint slides, interim president Josep Bartomeu, who had stepped in to replace Rosell, said the transfer was costing the club €57.1 million – the €17.1 million Santo transfer fee plus Neymar's €40 million – although there were a series of bonus payments worth millions more to the player and his family. Neymar would receive €500,000 per year to be a so-called ambassador for Barcelona in Brazil and his father would receive €400,000 per year to scout three young Santos players. All the payments were on top of Neymar's annual salary of more than €10 million. “We can't be any more transparent,” Bartomeu told reporters after the two-hour news conference.

Public prosecutor Jose Perals accused Barcelona of financial engineering by drawing up as many as nine separate agreements to avoid the club paying €12 million in tax. Barcelona should have withheld 25% of all payments to Neymar as income tax on non-residents, he said. Five days later, Barcelona paid €14 million to the tax authorities to cover a possible shortfall plus interest. At the same time it maintained its innocence, saying that it had acted on the advice of tax experts. That wasn't enough to get off the hook: the judge ruled there was enough evidence for Rosell to stand trial for “crimes against the public treasury” and for “dishonest” management. Cases, the pharmacist, had not intended to make such an impact and he withdrew his complaint from the Madrid court. It was too late. The court case was going ahead and Rosell faced up to seven years in prison if convicted.

Neymar's father, who was now enjoying the wealth he had negotiated for his family, said he had done nothing wrong. He wasn't charged with any crime and said he had paid all taxes due in Brazil. Dressed in a white shirt, purple tie and suit and carrying a black Louis Vuitton briefcase, the former mechanic turned up at court in Madrid to give evidence to judge Ruz, winking and flashing a thumbs-up sign to press photographers.

In Brazil, he rebuffed claims by Sonda, the supermarket chain owner who had paid him about €1.8 million for 40% of Neymar's transfer rights, that he should get a bigger return on his investment than 5 million euros. The wealthy investor argued that the deal was structured to keep the transfer fee low and reduce his share of the money.

Neymar's father said that Sonda had no reason to complain. He had received a return of almost 280% on his original investment. If he'd invested in the Brazilian stock market, he would only have got a return of 21% over the same three-and-a-half-year period. If he had invested in dollars to gain in value against the Brazilian real, he would be sitting on a loss. Neymar Sr. said that all he had done was negotiate the future rights of his son, the prodigy who was emerging as a global superstar on a par with David Beckham at a time when football was bigger business than ever. He was leveraging demand in the same way businesses did. “Can't a club negotiate its future television rights? Or a farmer negotiate on the price of his harvest before planting his crops?” the former mechanic said. “Those are simple analogies to explain the business model we used.”

As Barcelona grappled with the scandal, Atlético Madrid owner Miguel Ángel Gil was enjoying a relatively peaceful time thanks to the finance he had negotiated with a new group of lenders. However, he continued to look for more long-term backing. As part of a deal with billionaire Wang Jianlin – China's richest man – Gil had welcomed 20 Chinese schoolchildren between the ages of 13 and 15 to the club. The youngsters, who had never travelled abroad before, had arrived wide-eyed at Madrid's Barajas airport dressed in suits and ties, and posed for a photograph with tiny Chinese and Spanish flags. In a talent sweep of the country, they had been identified for their athletic skills at individual sports like table tennis and badminton. Football was barely played in Chinese schools, although the government was trying to change that. After all, football diplomacy had the potential to be far more powerful than the so-called ping-pong diplomacy of the early 1970s, when the Communist state had invited the American table-tennis team to visit.

Wang, chairman of the Dalian Wanda Group, was buying up property in London and film studios in Hollywood as part of an international push by China. He was also among the business elite who had been entrusted by the Chinese government to develop football in the world's most populous country, whose national team was ranked world no. 97 by FIFA, below the likes of Benin, Guinea and Guatemala. Chinese vice-premier Liu Yandong approached Wang. “Comrade Yandong spoke to me in person, hoping that I would take the task to help rebuild Chinese football”, Wang said before the children were dispatched to Atlético in 2011.

Spain, which had recently won the World Cup, had been identified as the best place for Chinese children to hone their skills. Two other groups of 20 children were sent to Valencia and Villarreal, clubs in the east of Spain. Under the three-year deal, each club would get €3 million. That was a valuable contribution to Atlético Madrid's finances, but Gil also saw the possibility of more cooperation with Wang Jianlin that could make the team part of the nascent boom in football in a country of 1.4 billion people.

The children studied Spanish and English, as well as following the Chinese curriculum, and trained at Atlético Madrid's training complex with teenagers of the same age. While they learnt to pass and head the ball, the concept of tackling another player was alien and they were uncomfortable using aggression to bustle another player off the ball. It was going to be a steep learning curve, but eventually the idea was for them to return to China and improve the standard of the new Super League.

In 2014, Wang Jianlin went to meet Miguel Ángel Gil to see how the children were getting on. It was a chance for the two men to get to know each other better and they talked courteously about business through an interpreter. Wang left Spain a few days later after buying a skyscraper in Madrid's emblematic Gran Via for €265 million – 32% less than it had cost at the height of Spain's property bubble.

A few weeks later, Gil travelled to Bengal to announce that the club had agreed to take a 25% stake in one of the franchises in a fledgling new football championship in India: Atlético Kolkata. The league's backers including Rupert Murdoch's 21st Century Fox and IMG Worldwide were keen to draw on the popularity of European football brands. Atlético would be giving its know-how but little if any cash. In return, it would plant a seed in the cricket-mad nation of 1.3 billion people that could flourish if the league took off and perhaps win it millions of new fans.

The franchises hired footballers such as David Trezeguet, Alessandro del Piero and Freddie Ljungberg. The veterans, nearing the end of their careers, were put up in luxury hotels while they trained and played in the country between September and December. With the first season barely over, Gil was back in Asia to cement a new deal with Wang Jianlin. The billionaire had seen first-hand how the Chinese teenagers were improving. They passed the ball crisply in the Spanish style mastered by Iniesta and Xavi, known as “tiki-taka”, and while there was not a superstar like Messi amongst them, they clearly had talent. Some had even learnt a dark art from their Spanish peers: how to dive to win a penalty. Now Wang wanted to increase the number of Chinese youngsters coached by Atlético's youth-team coaches to 144 within two years. In return, the Dalian Wanda Group he led would pay €45 million to take a 20% stake in Atlético from Gil and co-owner Cerezo. One of Wang's executives, Zhang Lin, joined Atlético's board. The Chinese billionaire also agreed to invest another €15 million in the sports facility where the youngsters trained. It would become known as the Wanda Atlético Madrid training centre.

In one of Dalian Wanda's hotels in Beijing, Gil had a pink orchid placed into a jacket lapel by one of the hostesses at the signing event to mark the first foreign shareholder in Atlético Madrid. For Gil, whose stake was reduced to 52%, the cash injection was another step away from the dark days of the financial crisis and he was rewarded when he and the board awarded him a boost in annual salary to €650,000.

On the sidelines of the ceremony, after taking off the orchid, he patted himself on the back. In the space of a couple of years he had gone from scrabbling for cash to sealing a deal with one of the world's richest men. Sounding a bit like someone who has successfully quit smoking, he said he had weaned Atlético off doing transfer-right deals with investment funds. The Club now had resources of its own, not to mention a big cheque from UEFA for reaching the Champions League final. “We have seized the opportunity that the financial crisis brought,” Gil said.

Back in Europe, clubs in Portugal and the Netherlands were among those having more difficulty navigating past the turmoil of the credit crunch.