Brazilian defender Douglas has rejected Hannover's first contract offer, according to Bild.
Douglas, 25, is a free agent after his contract expired at FC Twente, where he spent six years having signed from Joinville in 2007.
Liverpool and Newcastle United have both been linked with the centre-back, but Hannover are reported to have firmed up their interest with an approach.
However, Bild reports Douglas has turned down their offer of a four-year contract with a salary of €1.4 million, as he is seeking €2 million with a signing on fee of €1.5 million.
Hannover are apparently set to make a second approach, with the club keen to bolster their backline after they failed to land Arsenal's Johan Djourou, who has gone on loan to Hamburg.