The Guinean international has been earmarked as Celta Vigo's marquee sale since the start of the summer as the club looks to balance its books, with reports elsewhere putting the fee under discussion at around €18m as talks with an Italian club progress.
Losing Moriba would force Celta into finding a replacement of similar quality, or accelerating the promotion of academy midfielders Andres Antañón and Higo Burcio, both players the club trusts fully - though doing so would also create a headache for Celta Fortuna, the reserve side, who would lose two key pieces from their squad.
Moriba's exit is not the only departure being weighed at Balaídos. Carlos Domínguez, Manu Fernández and Carles Pérez are also among those whose futures remain open, while the future of Matías Vecino is similarly unclear.
Celta must also decide in the coming days whether to keep Hugo González involved with the first team, even though doing so would strip the reserve side of its standout player during what has been a historic season in Segunda for the group.
Beyond the outgoing business, Celta's priorities on the incoming side remain clear. Sporting director Claudio Giráldez has asked for reinforcement in attack after a move for Fer López proved impossible, while the club still needs to add to its goalkeeping options with the imminent arrival of Altay Bayindir from Manchester United.
Moriba joined Celta permanently last year for around €6m having previously spent time on loan at the club from RB Leipzig, and has become one of Giráldez's most trusted midfielders since.
Celta's asking price is understood to be significantly higher than the fee currently being discussed, though the club's improved financial position following a run to the Europa League quarter-finals has eased some of the pressure to sell at any cost.