Buchanan moves on-Loan to Villarreal for a reimbursement of € 1 million with the option for a permanent transfer worth € 13 million.
Villarreal reached an agreement for Buchanan prior to the competition from Monza, Torino and Fiorentina in Italy.
Buchanan has fully recovered from a leg fracture that suffered at the end of the season.
The winger will immediately be under the orders of Marcelino, although the Asturian coach will not count on him for today's match against Valladolid, who will view the player from the box in the Estadio de la Cerámica.