Celtic have told Fenerbahce of their interest in £5m-rated midfielder Stephen Appiah, BBC Sport believes.
Stephen Appiah played for Ghana at the World Cup finals
But the Scottish champions face competition from a number of other clubs for the 26-year-old Ghana international's signature.
Schalke, who finished runners-up in Germany's Bundesliga, have been linked with Appiah, who helped Fenerbahce to the Turkish title this season.
Appiah played for his country in last year's World Cup finals.
However, he is likely to be just one of a number of players on Celtic manager Gordon Strachan's list of possible summer signings.
With Celtic outgunning city rivals Rangers in the financial resources stakes, the rumour mill is rife in Glasgow about where Strachan will spend his cash.
He has already signed strikers Scott McDonald, who cost £700,000 from Motherwell, and Chris Killen, who was out of contract with Hibernian.
Scotland midfielder Scott Brown has also arrived from Easter Road for £4.4m.
Celtic are believed to have been interested in bringing Craig Bellamy back to Glasgow and the Wales striker was thought to have been extremely interested.
But it is believed that Liverpool's price tag of up to £9m will ward off Strachan's interest.
Celtic are known to be interested in West Brom midfielder Jason Koumas, but the Wales international is more likely to join a Premiership club in England.
Wage restrictions would also put paid to rumours that Arsenal winger Freddie Ljungberg was at Celtic Park for signing talks on Thursday.
Of those names doing the rounds, Manchester United reserve striker Giuseppe Rossi is a more realistic loan signing.
Celtic have also made an inquiry to Kilmarnock about Rangers target and Scotland squad striker Steven Naismith.