Barcelona have a reached an agreement in principle with Brazilian club Gremio to sign midfielder Arthur next year in a deal worth up to 40 million euros ($49.2 million), according to reports in Spain on Wednesday.
"FC Barcelona have taken an almost definitive step to seal the recruitment of Arthur," wrote Catalan daily Sport, who reported the transfer fee would be 30 million euros with a further 10 million in bonuses.
Mundo Deportivo claimed Barca director of football Robert Fernandez went to Porto Alegre "to seal the transfer of Arthur, with whom the club have reached a deal starting from January 2019".
The 21-year-old is expected to arrive during next season's winter transfer window, although Madrid-based Marca suggested he could join the club this summer if Barca reduce the number of non-EU players in their squad.
Arthur starred in last year's Copa Libertadores final as Gremio defeated Lanus of Argentina 3-1 on aggregate to claim the title for a third time.
But a leaked photograph of Fernandez alongside the Brazilian in a Barca shirt sparked controversy with the player still under contract at Gremio.