New Barcelona signing Junior Firpo seen taking on Antoine Griezmann, who also recently joined the Catalan club. Photo: Juan Medina/Reuters

BARCELONA – Barcelona signed left back Junior Firpo from Real Betis for 18 million euros (20 million dollars) plus a potential 12 million more in variables, the clubs said on Sunday.

The 22-year-old Spain under-21 defender will compete with Jordi Alba for a place in the Spanish champions's side and has a 200 million euro release clause.

"His height, speed and precision make him one of the most promising left-backs in European football," the Spanish champions said in a statement on Sunday. 

"One of the young talents that shone brightest during the past year in the league, Junior is a real handful for rival defences," the club continued.

Firpo joins other close season signings Antoine Griezmann, Frenkie de Jong and Neto at the Camp Nou. Barcelona open their title defence, and the Primera Division season, away to Athletic Bilbao on August 16.

Barcelona were in the running to sign former Ajax Amsterdam defender Matthijs de Ligt, who opted to join Italian champions Juventus instead.