Schalke remain hopeful that Klaas-Jan Huntelaar will sign a new contract with the club but general manager Horst Heldt has conceded the search for a replacement is already under way.
Huntelaar, 29, is in the final year of his contract at Schalke, and Heldt said in September that talks over an extension had reached a standstill.
The Bundesliga side have not, however, given up hope that the Netherlands international, who signed at Veltins-Arena from AC Milan in 2010, will commit to a new long-term deal.
"Certainly, we have hope," Heldt told DerWesten. "Klaas-Jan has not extended his contract, yet. He wants to focus on other things. That's legitimate.
"It is important he applies himself, plays successful football and 100% identifies with the region and the club.
"We would like to extend, as he is a first class striker, who will again add many goals to his name this season. But - like always in the past two years - we expect the worst, not the best. And look for alternatives."
The side's boss, Huub Stevens, is also in the final year of his contract, but Schalke are in no rush to begin negotiations.
Heldt said: "We both agreed upon taking our time and see how the season works out. We will find a date to talk about whether we continue working together. That date will be set by Huub and me."