Borussia Dortmund are reportedly considering moves for Bayern Munich defender Daniel van Buyten and Frankfurt stopper Sotirios Kyrgiakos.
Dortmund boss Thomas Doll is desperate to strengthen his backline after a disappointing start to the season and could be preparing to spend during the January transfer window.
According to Bild, Doll is preparing a fresh attempt to bring Van Buyten to the Signal Iduna Park after failing in his efforts in the summer.
Van Buyten, who starred for former club Hamburg under Doll, is known to be unhappy at Bayern Munich after losing his first-team spot to Martin Demichelis this season.
Kyrgiakos has impressed for Frankfurt this term and is also reportedly a target for Doll, although he is likely to face competition from Bundesliga rivals for the Greek star.
"I have head that we're supposed to be interested in him," Dortmund sport director Michael Zorc told Reviersport.
"But as the next transfer window is approaching it is our policy not to comment on any names."