Nottingham Forest have been told that they will have to pay between £12.8million and £17million if they are to sign Stuttgart defender Konstantinos Mavropanos.
Mavropanos, 25, has a release clause of £21million but Stuttgart are prepared to let him leave for a lower fee.
According to BILD, Eintracht Frankfurt and Napoli are also interested in Mavropanos, who has previously been linked with West Ham.
It is expected that former Arsenal centre-back Mavropanos will depart Stuttgart this summer, although his destination is currently unclear.
Speaking in May about his future, Mavropanos said: 'I can't make any promises because sometimes things in football can change from one day to the next.