Joao Mendes de Assis Moreira, 17, is training with Barca's Juvenil A side pending a decision on whether to hand him a permanent contract.
The teenager has been playing for Cruzeiro since he was 14 but recently rescinded his contract with the Brazilian side.
Joao Mendes, who has been joined in Barcelona by several members of his family, is a left-footed forward who can play across the front line.
His career is currently being overseen by his uncle, Roberto de Assis Moreira, who also played an active role in Ronaldinho's playing career.
The source asked for "patience," explaining that there is no rush to take a decision and that it needs to be remembered that it takes time to adapt to a new country coming over from South America.
Ronaldinho spent five years at Camp Nou between 2003 and 2008 and his time at the club is remembered fondly in the city.
He scored 94 goals in 207 appearances for Barca, helping them win the Champions League in 2006 and two LaLiga titles.
His son is now training with Barca's U19 team, who are coached by Oscar Lopez and assistant Javier Saviola, the former Argentina striker who played alongside Ronaldinho.