Sevilla defender Diego Carlos has informed the Spanish side that he wishes to leave.
The Brazilian centre-half is a key target for Eddie Howe's Newcastle United this January.
Sky Sports reports Carlos wants to move to Newcastle immediately, and has told his club as much.
Sevilla are willing to do business with the Magpies, but Newcastle are wary of overpaying for the 28-year-old.
Newcastle want to sign two centre-backs this month.