Picture the scene. The crowd of 65,000 soccer fans at the Estadio de Sao Paulo in Brazil is going wild. It's the 2014 World Cup and we're moments away from kick off.

A half human, half machine - enters the stadium.

As it walks onto the pitch with slow, jerky movements, billions of people - those in the stadium and those in front of TVs all over the world - are transfixed by its mechanical legs.

It kicks the ball, the first of the World Cup, and the soccer party begins.

But this is not a scene from a science fiction movie. This will become reality at the opening game of the World Cup in Brazil on Thursday.

A mind-controlled exoskeleton will help a paraplegic youth kick the first ball.

For the first time ever, an international team of neuroscientists and engineers has managed to create a robot prosthesis, which can be moved solely by mind-power.

They have been working on the "Walk Again Project" since 2008, with the goal of giving millions of paraplegic people the ability to move independent.

That's the hope of Gordon Cheng from the Technical University of Munich (TUM), who is one of the leading scientists of "Walk Again."

"This project could be of great use to society, especially to those who can't walk, of course," Cheng says. "It's a wonderful feeling to know that all of our hard work will help these people."

Human brain, mechanical legs

Cheng and his colleague Miguel Nicolelis, the world's leading neurobiologist in the field of human-machine connections, had their breakthrough for the "Walk Again Project" back in 2008 when they succeeded in moving robot legs by mind-control.

The amazing thing was that the brain, belonging to a primate, was at Duke University in the US, while the legs were in a lab in Japan.

"That's when we knew that a biological brain could in fact control mechanical legs," Cheng says.

Cheng and his colleagues began building prototypes.

They developed sensors similar to human skin. With these, the wearer will be able to execute movements with the mind-controlled exoskeleton - and feel them too.

Wireless electrodes attached to the subject's head record his brain waves, which then signal the exoskeleton to move.

"Through vibrations, the person feels like he is touching the floor, moving his leg and kicking the ball," says Cheng.

An international project

The "Walk Again Project" is an international effort. The Duke University Center for Neuroengineering in the US, the Swiss Federal Institute of Technology in Lausanne, the International Institute for Neuroscience in Natal, Brazil, and two universities in California and Kentucky are all involved.

For the almost 200 scientists, it's not about the profit. They say they want to show how science can improve people's lives.

"Our experience has shown that the brain treats the machine like a natural body part - just like professional tennis players regard their racket as a continuation of their arm," says neuroscientist Miguel Nicolelis.

Practice with an avatar

The researchers have long been preparing for the decisive moment at the World Cup with a group of ten young paraplegic people. They set up a lab for a series of tests in Sao Paulo, where the group learned to interact with a virtual environment and a robotic tank top. It allowed them to "walk" without actually moving.

It's like a flight simulator, says Nicolelis. An avatar imitated all movements the young group made, so they could get a feel for the human-machine interaction - and enable them to control the robot with their thoughts.

On Thursday, a young man, who can't walk, will be on the pitch to open the 2014 World Cup in Brazil. And he will no doubt be one of the biggest sensations of the cup.