#5 Shkodran Mustafi - Arsenal
A bit of a left-field move this, but it has been made fairly public that Shkodran Mustafi was keen on leaving Arsenal on deadline day, with his family issues in mind. However, a move to Inter Milan broke down with the Gunners insistent on recouping his fee.
Real Madrid could easily pay the €40 million Mustafi cost Arsenal, and in return, would be getting a seasoned central defender who already has La Liga pedigree with Valencia. The German could provide the competition required for Raphael Varane that could ensure the Frenchman steps up a gear, without becoming too complacent.
Buying Mustafi would hinder Jesus Vallejo's development though, although that could be negated by sending him out on loan again, albeit to a La Liga club this time, to properly test him. However, a club like Real Madrid only has place for the very best, and if Vallejo is not up to the mark, Mustafi would represent the better option.