Schalke managing director Horst Heldt has indicated that the Bundesliga club would be prepared to consider selling the midfielder ahead of his summer switch to White Hart Lane
Holtby has agreed to join Spurs upon the expiry of his contract at the end of the season but Heldt says that Schalke would be prepared to consider selling him to the north London club before then.
The 22-year-old hinted that a deal could be completed earlier than the summer in a message posted on his Facebook account but also promised to dedicate himself to Schalke until he left the Bundesliga.
"If Tottenham ask for Holtby in the January window, we will talk to them about it," Heldt said. "Nothing has happened yet, but, from our point of view, we are prepared to speak to them.
"It would have to be done quickly, because we would have to find a replacement for him."
Holtby's father was born in Liverpool but the player elected to represent Germany and has so far made three appearances for the national team.