This article is part of the Guardian's World Cup 2014 Experts' Network, a co-operation between 32 of the best media organisations from the countries who have qualified for the finals in Brazil. theguardian.com is running previews from four countries each day in the run-up to the tournament kicking off on 12 June.

Even stern coaches such as Ronald Koeman and Louis van Gaal can't help but laugh when they see Bruno Martins Indi enter the training pitch. The big, bold defender, who has an intense look during matches, immediately runs up to his former youth coach Cor Adriaanse like a puppy, screaming "Uncle Corrie, Uncle Corrie, let me hug you!"

Martins Indi, who was born in the shadow of Benfica's Estádio da Luz to a Portuguese mother and a Guinean father and then moved to Rotterdam at an early age, is an endearing figure, capable of raising a smile from the hardest coach. He famously elicited the line – "I love you, Bruno" – from none other than Van Gaal.

"I think I click very well with Van Gaal. But I do it without sucking up to him, honest!" Bruno says in an interview that often feels like having a chat with a lively 10-year-old rather than a 22-year-old professional footballer.

The jump into the arms of "mister Van Gaal" after an important goal during Holland's march to qualification was "purely spontaneous", although it apparently frightened Van Gaal a little because he had just had a hip operation. "I think I let him slide off me quite well," the coach said later, making a rare joke to the media.

"BMI" is certainly a cheerful lad. When there is a business golf tournament and all the players are looking to leave as soon as they can, he's shouting that everybody should smile to the camera and keep their happy faces on throughout the day "because we are blessed to be here".

He loves to entertain. When Mario Balotelli did his famous how-do-I-get-out-of-my-shirt-act, the next day Martins Indi was giving a perfect imitation at the Feyenoord training ground all day.

Life wasn't always this much fun for the well-built left-footer who prefers to play as a centre-back. In the Netherlands he was mostly left to himself by his parents, trying to make his way in Slinge, a neighbourhood in Rotterdam with a high crime rate. He didn't have the easiest time there but doesn't want to discuss it, waving it away with a grin and saying: "Maybe I'll tell you about it later, friend. I can write a book about it. And it's not a very happy one. But now I have to keep my focus."

A life as a tearaway wasn't unthinkable, as he saw friends taking the wrong path and had to ask for handouts several times as a young player at Feyenoord because he was broke.

His young life desperately needed structure. Feyenoord helped him with that, filling out forms, getting him a decent roof over his head and applying for a Dutch passport so he could make his debut for Holland's youth teams. Soon the youngster who played as a striker at his amateur club, Spartaan 20, was starting to transform into a fearless defender.

He often had extra training sessions with Adriaanse when his team-mates had long since gone home and tried to organise his life by putting down his plans for the upcoming day in a book. Later on he also wrote down his deeper thoughts and started to collect proverbs and sayings. His favourite one is: "Let the best of today be the worst for tomorrow." It says something about his ambitious mind.

At just 19 he became a father, leaving the nightlife and streets behind him and fulfilling his dream to be "an ordinary person with a roof terrace and a garage".

However, it has proved difficult for Martins Indi to get a decent streak of games under his belt. Playing for the Oranje he gets all the trust from Van Gaal he could ask for, and the manager plays him in almost all of his games as a central defender. But at Feyenoord he has been switched from left-back to central defender to the bench, enticing several clubs, including Milan and Everton, to show serious interest in his versatility.

His best performance was probably against Dynamo Kiev in the preliminaries of the Champions League two years ago. After that match Van Gaal, who had not seen him before, immediately selected him for his first match on his road to Rio.

At their first encounter the young player had no hesitation in talking to the legend of Dutch coaching, informing him that "I would really like to become better. I would like to ask you a lot, Mr Van Gaal." Van Gaal shot back: "That's a good thing, because I can help you with that."

Martins Indi: "Really?"

Van Gaal, beaming: "I love you already, Bruno."

The manager looks set to keep the love going all the way to Holland's mouth-watering opening game in Brazil – a rematch of the 2010 final.

Bart Vlietstra writes for the Dutch newspaper De Telegraaf

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