Kevin Ramirez said he felt "disappointed" and "very hurt" at the singer's actions after he put his arm through the star's chaffeur-driven car to touch his face and neck outside the concert venue on Tuesday night.
It was initially reported the Spanish youngster, a Real Madrid fan who has met and got autographs from Welshman Gareth Bale and his teammate Cristiano Ronaldo, was a minor but today it emerged he is 18 and from the city of Mataro near the Catalan capital.
He revealed in a radio interview he had gone home after having his lip split by Bieber and abandoned plans to see him performing.
Calling the Canadian's actions "unnecessary", he added: "This matter is now in the hands of lawyers.
They will deal with it. I can't give out any more information at the moment."
The move makes it almost certain the Spanish teenager will now press charges against Bieber, although he steered clear of committing himself to suing Justin.
Police have described the incident as a "misdemeanour" rather than a crime but said Kevin is free to lodge a formal complaint against the singer at a local court or through them.