Celtic have expressed interest in Germany defender Alexander Madlung, according to the Wolfsburg player's agent.
The 25-year-old is the latest centre-back to be linked with the Parkhead club following a failed bid to sign Romanian Gabriel Tamas.
Agent Uwe Kathmann revealed Wolfsburg manager Felix Magath had informed the player of Celtic's approach.
Kathmann told the Scottish Daily Mail: 'Alexander called me on Tuesday and told me that 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 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.'
Celtic are also thought to have made a bid for Cardiff defender Glenn Loovens, who 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.'