Schalke coach Keller unsure on Holtby switch

The 23-year-old moved to White Hart Lane in January 2013 but has found his first-team opportunities limited at Spurs.

Having made just six starts in the Premier League this season, the German has been linked with a return to the Veltins Arena. 

Despite Spurs manager Tim Sherwood hinting that Holtby could be allowed to leave, Keller said it was unlikely Schalke could finance such a deal. 

"We can't really imagine such a transfer financially," he told Bild.

"Talks have not yet reached an advanced stage."

Keller did add that Holtby would represent a boost for his squad, with midfielder Jermaine Jones set to leave the club in the current transfer window.

"Lewis has already played as a defensive midfielder under me," Keller added. "He can play there and is tactically very well-schooled."

Holtby originally moved to Schalke from Alemannia Aachen before being loaned to Bochum and Mainz during his time at the club.