Barcelona have signed midfielder Arthur from Brazilian side Gremio in a deal worth 40m euros (£35.5m).
Arthur, 21, has signed a six-year contract at the Nou Camp after the clubs reached an agreement in March.
The deal, which includes a 400m euro (£451m) buy-out clause, will initially cost Barcelona 31m euros (£27.5m).
It comes a day after Brazil midfielder Paulinho left La Liga’s champions to rejoin Chinese club Guangzhou Evergrande on loan.
Arthur joined Gremio in 2010 from lower-league side Goias Esporte Clube and made his first-team debut, aged 18, under former Brazil manager Luiz Felipe Scolari in 2015.
He has been called up to the Brazil team in the past but has yet to play for them, and did not make their World Cup squad.
The midfielder helped Gremio win Brazil’s equivalent of the FA Cup, the Copa do Brasil, in 2016 and South America’s Champions League – the Copa Libertadores – in 2017.
Arthur was named man of the match in the second leg of the 2017 Copa Libertadores final as Gremio beat Argentina’s Lanus 3-1 on aggregate.
In total, he scored six goals in 66 appearances for Gremio.