The midfielder is believed to have caught the attention of the Primera Division table-toppers, who are eager to bring him back to the Santiago Bernabeu
Despite boasting a wealth of talent across midfield including Mesut Ozil, Kaka, Nuri Sahin, Xabi Alonso and Sami Khedira among others, the Santiago Bernabeu side are eager to bring the 27-year-old Valero back to the club.
Valero is a product of the Madrid youth academy, but never managed to break into the first team at los Blancos.
He eventually moved to Villarreal in the summer of 2010 after previous spells with Real Mallorca and West Bromwich Albion, and has since developed into a key player at the Yellow Submarine.
The Spain international has a contract until the summer of 2015 with Villarreal, and has a buy-out clause of 40 million euros.