A Gremio delegation is in Barcelona to complete the sale of Arthur Melo.
Sport says Gremio officials were in the stands for Barca's 1-0 win over Atletico Madrid on Sunday.
Barca chief Robert Fernandez was in Brazil last month to thrash out terms for Arthur and the deal is now expected to be finalised in Barcelona.
The young midfielder is expected to be sold to Barca for a fee of €30m with bonuses rising to €40m.
It is also expected to see Arthur spend the year at Gremio on-loan before joining Barca in January.