A documentary portraying Lionel­ Messi's tough route to the top was given a first screening in Rio on Wednesday.

The work, Messi, directed by Spaniard Alex de la Iglesia and scripted by former Argentina international Jorge Valdano­, shows how Messi battled a growth hormone disorder as a youngster before becoming a megastar at Barcelona.

"We know what a genius he is on the pitch, and we wanted to know how he is off it," said Valdano, a World Cup winner in 1986. "Although behind every genius lies an enigma I think we got close" to ­portraying the real man, Valdano said.

The film depicts the various stages of Messi's career, from playing in the streets in his hometown of Rosario to the would-be professional battling a growth hormone deficiency.

It then shows how he travels to Barcelona as a young teen looking to make it and then the tense wait as the club decide if he has what it takes to enter their youth ranks.

The film then shows how Messi broke into the Barca first team to play alongside Brazilian 2002 world champion ­Ronaldinho - but also his struggles to transfer effervescent club form to Argentina's national side.

His four world Player-of-the-Year titles are also touched on, as well as the role of his maternal­ grandmother in ­fostering his early passion for the game.

There is also a snapshot of his partner Antonella Roccuzzo - the pair were friends from pre-teen years.

Much of the film has ­Valdano debating Messi's qualities with former Barca coach Johan Cruyff in a restaurant interspersed with scenes of his life.

The work also contains ­observations from Barcelona stars such as Gerard Pique, ­Javier Mascherano, Jose Manuel­ Pinto and Andres Iniesta.

The documentary also looks at issues such as dressing room repartee, childhood friends and former teachers, as well as the decision by a club doctor to give Messi treatment for his growth deficiency.