Alexander Madlung's agent has claimed Celtic are interested in signing the Wolfsburg defender.
The German international has been linked with a transfer away from the Volkswagen Arena this summer, with Tottenham and Everton both rumoured to have previously shown an interest.
Celtic boss Gordon Strachan is still in the market for a stopper after ending his interest in Auxerre's Gabriel Tamas.
Madlung has emerged as a fresh target for the Parkhead club, although the player's agent, Uwe Kathmann, has hinted that the 25-year-old is not convinced his future lies in the SPL.
Kathmann told the Scottish Daily Mail: "Alexander called me on Tuesday and told me that (Wolfsburg coach Felix) Magath called him in and told him about Celtic's interest.
"He said Celtic wanted him and asked how he might feel about that. Alexander told him he was open to all possibilities but that Scotland would not be his first choice.
"Other big clubs are also interested, but Celtic are playing in the UEFA Champions League. The only concern for the player would be the Scottish league.
"We also have other possibilities, but those clubs are still deciding - Celtic are talking to Wolfsburg already."
The Hoops are also believed to have made a bid for Cardiff defender Glenn Loovens, who rivals Rangers attempted to sign last month.
Cardiff chairman Peter Ridsdale told the Daily Record: "I can confirm I've had contact from another Scottish club who made a bid for the player this week.
"That bid fell way short of Cardiff's asking price."