Gremio are said to be ready to report Barcelona to FIFA after their player, Arthur, was pictured in the latter's jersey.
As we can see here courtesy of AS, the 21-year-old was snapped in a Blaugrana shirt on Friday:
David F. Sanchidrian of AS reported that the image was put out by Globoesporte. The snap emerged after Barca's technical secretary, Robert Fernandez, was in Brazil to watch the player in person.
Speaking to Estudio Gaucha (h/t Sanchidrian), Gremio's legal adviser Nestor Hein has said the club will be taking action:
"This young lad Arthur is our player. As for the whole way it was orchestrated, he's not to blame. I've been told that Barca have planned to take Arthur and his family to lunch today.
"Gremio can't stop him from doing that but Barca are creating problems with Gremio by trying to influence the kid. We're putting together a formal complaint to submit to FIFA accusing Barcelona of manipulation as soon as we have full confirmation about the way they acted."
It's noted in the report that Hein was keen to make it clear that this incident is not the player's fault. In addition, Gremio are said to be unwilling to do business with the Blaugrana for the midfielder, who has a €50 million (£44 million) release clause in his contract.
Spanish football journalist Rafael Hernandez believes that if this deal is close, the leaked image may be detrimental to Arthur getting a move to the Camp Nou:
It'd be a shame for the player and the Blaugrana if a deal was scuppered, as Arthur has showed a massive amount of promise early in his career.
These numbers from the FootballTalentScout Twitter account offer an insight into how talented a player he is:
The youngster has been operating at the hub of the Gremio side and has been a controlling influence on their play. The Brazilian youth international can take the ball in tight spaces, wriggle out of trouble and bring team-mates into the game with his smart passing ability.
He boasts the types of attributes long associated with the Blaugrana and would likely be a big hit if he did move to the Camp Nou. But as things stand, that's seemingly no longer a surefire prospect.