There is a saying in Brazil that a great footballer is born here every day.
A stroll along Rio's breathtaking beaches is enough to show you why they believe that. As far as the eye can see, footballs dance in the evening air, propelled by one deft touch after another.
Alongside the sun-worshippers, towel hawkers, muscle-men and bar-crawlers are boys and girls, men and women, repeating skills and drills, honing their feel for the football, hour after hour.
|Futsal: the rules|
|Five players per team, including the goalkeeper. Rolling subs are permitted||Matches consist of two halves of 20 minutes|
|Ball weighs 420 grams - around 80 grams heavier than a typical football.||Court is between 28m and 40m long, and 15m and 20m wide|
Tempting as it is to conclude that Brazil's success stems from this carefree childhood practice on the sand, the real reason may lie elsewhere.
In these parts, they believe Futebol de Salao - or futsal - is the game that made Brazil great.
Pele, Zico,Socrates, Romario, Ronaldo, Neymar are just some of the Brazilian national icons who spent their youth playing with the smaller, heavier futsal ball - a ball that could not be lofted into the air, but demanded speed of mind, fleetness of foot, flair and flamboyance.
"Futsal makes you think fast and play fast," Pele said. "You try things, it makes you dribble. It makes you a better player."
In Fortaleza, in the north-east of Brazil, some of the region's best young players train in the stifling midday heat. The basketball-size court is surrounded by stepped concrete seating, painted yellow and blue. A group of spectators look on as the ball skims around in a blur of artistry, fizzing frequently into the small goals.
It is the ball that makes the game. According to one version of futsal history, the ball is weighted because it was began on courts surrounded by windows - near impossible to kick into the air, the heavy ball was therefore less likely to break glass. But whatever the origins, the weight and size compels a certain brand of football - a style Brazil made their own in the early 1970s.
And it is a style you can still detect today. Watch Neymar closely and you will see him use techniques he developed playing futsal. The Brazil No 10 often traps and then shifts the ball with the sole of his foot, rather than the instep, a skill young Brazilians use on court in every game.
"Football owes futsal so much," said Manuel Tobias, one of futsal's greats and three-time world futsal player of the year, watching the youngsters in Fortaleza. "If we look at the Brazil team in this World Cup, around 10 players were registered with futsal clubs. Neymar, Willian, David Luiz, Daniel Alves, Luis Gustavo, Marcelo - they are a different type of player.
"They think fast, they are skilful and they are able to get out of difficult situations."
Oscar is another Brazil player whose game has been shaped by the sport. His goal against Croatia in the opening game of the World Cup was dismissed by many as a tired toe-poke. The Chelsea midfielder had a different view.
"It was like something you might do in futsal," he said."When you get the chance you just shoot. You don't wait."
With space limited on the futsal court, players do not have time to pull their leg back for a shot. Romario, a World Cup winner in 1994, was the master of the art.
"The best player I have coached? It has to be Romario," Johan Cruyff once said. "His technique was extraordinary. Curiously, most of his goals were toe-pokes."
There was nothing curious about it. Futsal had helped him develop a technique of finishing without warning and often just when defenders felt they had closed him down.
The great dribblers of Brazilian football also came from futsal. Garrincha was arguably the greatest of them all. Former Wales international left-back Mel Hopkins, who lined up directly against Garrincha at the 1958 World Cup, told BBC Sport. "His legs went one way and his body the other."
Rivelino, Ronaldinho and even Neymar have developed a dancing, elastic sway to their dribbling that is uniquely Brazilian. Some describe it as 'ginga' - a loose body. Again it is born of necessity, the need to find a way beyond your opponent in the close confines of a futsal court.
"Because you play in a small space you have to know what you are going to do before the ball gets to you," former Brazil international and BBC pundit Juninho said. "I was six when I started. It has helped Brazil a lot over the years."
|Futsal's world order|
|Brazil are historically the strongest futsal nation, with five World Cup titles, including the last event in 2012|
|Spain are the only other nation to have won the World Cup, with two titles|
|Italy, Argentina and Portugal are also currently ranked in the world's top 10, along with Iran and Azerbaijan|
|England are currently ranked 73rd, below Turkmenistan and New Zealand, and one place above Andorra|
The origins of the sport are a matter of debate. Some believe it began in the Young Men's Christian Associations (YMCA) in Montevideo, Uruguay, at a time when the church used sport to instil moral values, like discipline and honour.
Others believe Brazil invented the game, as the urban sprawl of cities such as Rio and Sao Paulo wiped out the space for 11-a-side pitches.
What is not disputed is that the rules were formalised in Uruguay as a combination of basketball, water polo, handball and, of course, football - 20 minutes each way, five or six-a-side.
Since then its practice, and its influence, has spread. The first futsal World Cup took place in 1982, Brazil winning the final in Sao Paulo - and four or the first five tournaments. Fifa began to take notice and in 1989 took control of the sport.
With wider popularity came changes. With television companies interested, Fifa made the ball twice as big - a size four rather than the size two with which the game began - and much lighter. Spain began to take futsal seriously, using Brazilian-born players to strengthen their team, winning futsal's World Cup twice. It soon became a regular part of the academies at Barcelona, Real Madrid and elsewhere in La Liga.
"In futsal, you see whether a player is really talented," Spain midfielder Xavi - winner of football's World Cup and two European Championships - said. "In normal football you don't necessarily identify talent as easily because it's so much more physical. But with futsal, you notice small details in quality, class and tactical understanding."
|Futsal's footballer endorsements|
|World Cup winner Pele: "Futsal was important in helping to develop my ball control, quick thinking, passing… also for dribbling, balance, concentration…futsal was very, very important, no doubt."||Argentina's Lionel Messi: "In Argentina, when I was a young boy, I used to play a lot of futsal on the street and with Newell's Old Boys. It was a really fun game that's helped me a great deal."|
|Real Madrid forward Cristiano Ronaldo: "The smaller court helped my footwork skills, the nature of the game made me feel so free when I played. If it wasn't for futsal, I would definitely not be the player I am today."||Milan and Brazil forward Robinho: "It helped me to become the player I am today. There you don't have time to think, you are always tightly marked and you develop a sense for performing in small spaces."|
Portugal, Italy and Germany have, like Spain, been playing the game for the past 20 years in an attempt to emulate Brazil's technique, and England is belatedly catching on, albeit gradually.
It is 20 years since schoolteacher Simon Clifford returned from Brazil, a trip he paid for with a £5,000 loan from a teaching union, determined to spread the gospel in England. Clifford's Brazilian Soccer Schools have been doing that for almost 20 years and the game is, at last, beginning to take off.
In Brazil, there is no sign of its popularity waning. Indeed, according to Louise Bede, vice-president of the Brazilian Futsal Association, it is more popular now than ever.
"Government figures tell us futsal is the most popular sport in Brazil even more so than conventional football," she said. "The athletes who started with futsal are the cornerstone of the Brazilian squad."
The game is played in all Brazilian football academies, and is part of what distinguishes coaching in the country, where the biggest fear is over-coaching its next generation of boys and girls, not under-coaching them.
Coaches are discouraged from giving players formal positions until they are 14. Talent is allowed to breathe, to find its natural path in games such as futsal. From the age of seven to 12, young players tackle futsal three days a week.
It remains to be seen whether the adapted, TV-friendly version of the game will have an impact on Brazil's fortunes on the world stage in the long term. What is clear, however, is that it is still regarded as the incubator of Brazilian talent.
Futsal is proof that in Brazil - despite that popular saying - great footballers are not born, they are made.
For the best of BBC Sport's in-depth content and analysis, go to our features and video page.