Here's what world's best chess player Magnus Carlsen was like as a kid

Before Magnus Carlsen amazed the world with his prodigious chess talent, he was just a kid lost in deep thoughts. His dad was even a little worried about him.

"I was a bit concerned about the relatively development compared to other kids," Henrik Carlsen says in "Magnus," a new documentary. "It was kind of hard to give him instructions on how to do things physically and it would be difficult simply to show him. He's got to think about it."

The documentary, directed by Benjamin Ree, features extensive archival footage and home movies of the Norwegian chess player from infancy to age 22, when he won the world championship. It's a rare and scintillating look on the emergence of a genius.

"We introduced him to this flag book when he was four, and there he could read all about the countries in the world and municipalities in Norway," Henrik says. "After some time I think he knew all the countries, all the capitals, the same for most of the municipalities. My impression was that the numbers were telling him a story or more specifically showing him a picture.... I told my wife that I think he can become a good chess player because he had these traits."

Magnus learned to play chess at the age of five. He played his first tournament at the age of eight. He was a Grandmaster by the age of 13.

He did it while studying less than most serious chess players.

"Most of the strongest chess players in the world have learned this vast knowledge base through brute discipline. Long working hours, a lot of homework, and strict teachers," Henrik says. "People told us that Magnus should do it this disciplined way and that if he didn't do it, he might waste his talent."

Not Magnus. "I don't do much serious work on my own," the then-teenage player said on camera (translated).

"Whether he was thinking about chess or reading 'Donald Duck,' he was using the same playful approach, using his intuition, his curiosity," Henrik says.

Carlsen takes pride in being well-rounded and approachable.

"I'm not one of those, for lack of a better terms, borderline nutcases," he says in the documentary.

Carlsen expressed a light-hearted philosophy in a 2013 interview with Business Insider: "For me, it's about playing as long as I'm motivated, as long as it's fun, as long as it's interesting."

Carlsen went on to win the World Championship in 2014 in an epic clash with Viswanathan Anand, one of the most rigorous preparers in chess history.

"Magnus" opens in theaters in NYC on Nov. 18 and in other cities Nov. 25.