The Germany international has just over six months to run on his current contract with the Bundesliga side, making him eligible to sign a pre-deal at the turn of the year.
Schalke, though, look determined to retain the midfielder’s services and are said to be ready to make him the highest paid player in the club’s history, leaving the 22-year-old with a big decision to make.
He said: "I have to find out for myself what the next step should be.
"I have to consider a million things. I am a person who is very meticulous in such decisions. I play through all the scenarios. So I need time.
"There doesn't exist a deadline, but I think we are in the final phase.
"'The final decision will be made in January."