Toby Alderweireld's wage demands have brought talks with Tottenham over a contract extension to a standstill.
It is believed the Belgian, 29 next month, is seeking a five-year contract and a salary far in excess of the club's £110,000-a-week pay ceiling.
Talks are close to breaking point as there is such a distance between the two parties.
Real Madrid are understood to be monitoring the situation closely.