Neven Subotic is the latest defender to be linked with Celtic.
According to the German website Fussballeck the 29-year-old is wanted by both Celtic and St Etienne.
Subotic has been with Borussia Dortmund for a decade but has drifted out of the first team picture over the last 18 months.
There’s little doubt that Celtic are in the market for experienced central defenders but it’s difficult to judge if there is genuine interest in the Serb or just a creative agent drumming up interest in a client.
Celtic did sign Marvin Compper from the Bundesliga earlier this month but the former RB Leipzig defender will be out of action for a couple of weeks with a calf injury.
In midweek Erik Sviatchenko moved out on loan with Kris Ajer and Dedryck Boyata the current first choice central defenders.
Celtic’s other January signing, Lewis Morgan was in action for St Mirren against Aberdeen in today’s lunchtime Scottish Cup tie.