According to The Sun, the La Liga club have listed the playmaker as a potential target this summer.
The Dane has developed into an integral player for Tottenham since moving to north London from Ajax in 2013.
And the 25-year old says he would like to continue his career at the "highest level."
"In the future I see myself at the highest level. That's what I dream about."
"It can be about two to three years. It may be in another club or it could be Tottenham if we have come all the way up."