Antonio Rudiger has reportedly been left "dissatisfied" that Chelsea have failed to improve on their recent offer of a new contract.
The Germany international has started all but one of Chelsea's Premier League and Champions League fixtures, his only absence due to a minor back injury.
However, despite his status in Thomas Tuchel's squad, the 28-year-old remains with less than nine months remaining on his current deal.
According to Bild journalist Christian Falk, Rudgier is disappointed that club officials have not made more of an effort to meet his demands.
Falk claims that the Blues have not improved on their offer from the start of the season, a stance which has inevitably left other clubs monitoring the situation.
Real Madrid and Bayern Munich are known to be admirers of Rudiger and hope to hold discussions with him in January.
