The 23-year-old midfielder has been a key part of Jorge Jesus’ Flamengo side, leading to European interest.
A Premier League team, believed to be Tottenham, had an €18m bid rejected for Gerson last week.
Flamengo are waiting for an offer of €35m-plus for Gerson, who had a spell in Italy with Roma and Fiorentina between 2016 and 2019.
Gerson has a €75m release clause and the Flamengo board have set €35m as the starting point for talks.
According to Fox Sports Brasil, Chelsea and Dortmund have a definite interest and could make bids in the coming weeks.
The belief is that Gerson, who is under contract with Flamengo until 2023, will move to Europe again this summer.
Flamengo’s financial situation means they need money and selling Gerson who ease the pressure on them.
Gerson has yet to break into the senior Brazil squad, but a big move to England or Germany could lead to a call-up.
In last season’s Série A, Gerson made 27 appearances for Flamengo, scoring twice and delivering three assists.