Manchester City reportedly fear that midfielder Ilkay Gundogan could leave the club for free when his contract expires next summer.
The 32-year-old has spent the last six-and-a-half years at the Etihad Stadium and was elected the club's new captain at the beginning of this season following the departure of Fernandinho.
Gundogan remains a first-team regular under manager Pep Guardiola and has starting 12 of his 15 appearances for the Citizens across all competitions this season.
However, speculation continues to circulate about the midfielder's future at the Etihad, with the German able to negotiate pre-contract agreements with foreign clubs from January onwards.
According to Football Insider, Man City have made contact with Gundogan's representatives over extending his contract but both parties are yet to reach an agreement.
Barcelona, Juventus and Bayern Munich have all been credited with an interest in signing Gundogan, although the latter are understood to have pulled out of the race for his signature.
Meanwhile, Galatasaray are the latest club to express their interest in the midfielder, who is of Turkish descent and recently admitted that a switch to the SuperLig is under consideration.
"Because of my roots, Turkey is naturally interesting. I also like the USA, I've been there on vacation several times," Gundogan told Sport1.
On his contract situation at Man City, Gundogan added: "I'm not worried about that at the moment. I still have a contract in Manchester until 2023, I'm very happy there, both in sporting and private terms, and I can theoretically imagine ending my career with City."
Gundogan was Man City's first signing of the Guardiola era back in 2016 and the Spanish manager has recently heaped praise on the midfielder, describing him as a 'joy' to work with.
"Gundogan was the first player we signed when I became a manager. It is a pleasure to work with people like Ilkay," Guardiola told mancity.com last week. "I will never forget him. For me personally and for the team, he is an incredible football player, always grounded.
"He likes to be second position and always you can rely on him 100%. He gave us the Premier League (last season). He can play holding midfielder and attacking midfielder. He is so smart, can talk about the world.
"That is why he was voted by his mates as captain. We are incredibly happy with the decision we made to have him. In the first year he had an ACL injury but from the second season when we started winning the titles, he was there. It's a joy to have these human beings with you."
Gundogan has made a total of 269 appearances for City across all competitions, scoring 51 goals and providing 34 assists.
The 62-cap Germany international has also won a total of 11 trophies during his time at the Etihad, including four Premier League titles.