Atletico Madrid have asked about taking Caglar Soyuncu from Leicester City in the January transfer window.
Atleti boss Diego Simeone is believed to be keen on rebuilding his defence after a shaky few months, and sees the Turkey international as part of the solution.
However, a deal is considered highly unlikely with the 26-year-old expected to agree a pre-contract instead for the summer when he is a free agent.
The Foxes have already lost one key defender this season, after Wesley Fofana joined Chelsea in August following weeks of speculation.