According to the Brazilian media, La Liga giants Barcelona have agreed a €40 million (£35m) deal to sign Arthur from Germio.
The Catalan side have been in talks with Gremio for several months, while the 21-year-old attacker was pictured wearing a Barcelona shirt after holding secret talks back in December.
The highly-demanded South American is widely regarded as one of the most talented youngsters in Brazilian football and has been also been linked with Chelsea and Manchester United. But UOL Esporte claim that Barcelona and Gremio have finally agreed the terms of a summer deal.
It also believed that Camp Nou will pay €30m up front, plus another €10m in add-ons related to appearances and the midfielder’s first contract renewal.
Arthur, who has not featured for Gremio in 2018 due to an ankle injury, will remain with the Brazilian club until December and will join Barca in January of 2019.
The Gremio No.29 has represented Brazil at under-17 and under-20 levels but has not yet featured for the senior side, although the creative youngster did receive a call-up for a Selecao in September.
Alongside Arthur, Chelsea are also interested in signing AS Roma midfield star Radja Nainggolan, who has failed to join the Blues in January transfer window.