Tottenham have had another offer to take Lewis Holtby to White Hart Lane in January knocked back by Schalke.
Holtby agreed a deal to join Tottenham in the summer when his contract with Schalke expires earlier this month.
However Spurs are now keen on brining the move forward after midfielder Sandro was ruled out for the remainder of the season with a knee inury.
The north London club had an offer of just under £1 million rejected initially, and have now failed with a “slightly increased” bid according to Schalke’s General Director Horst Heldt.
"Spurs have increased their offer for Holtby, but only slightly. But it is still not acceptable. We have to wait," he told reporters.
He added: "Tottenham have only marginally improved their offer for Holtby, but it remains unacceptable for us. We will have to wait to see what happens.
"Feasibility is what it's all about, not wishes."
Holtby starred in Schalke’s 5-4 win over Hannover last week, scoring once and setting up two others.
Die Königsblauen coach Jens Keller admits he would like to keep the attacking midfielder until the end of the summer, but concedes money will be the ultimate decider.
"Lewis put in a great performance against Hannover. It would be good if he stayed here. But we have to take the financial side into account as well," he told reporters.
Holtby, whose father is English and supports Everton, has earned three caps for Germany after opting to represent his country of birth instead of the Three Lions.