Villarreal have confirmed that Cristian Zapata is to join AC Milan from Villarreal on a season-long loan deal.
Colombia international Zapata, 25, has passed a medical and will help fill the void created by the departure of Thiago Silva to Paris Saint-Germain.
A statement on the Villarreal website read: "Villarreal and Milan have reached an agreement to transfer Cristian Zapata for this season. Thus the Colombian defender will return to play in Italian football with the Rossoneri."
Milan are reported to have the option to complete a permanent deal for Zapata, who returns to Serie A one year after leaving Udinese.
Villarreal, meanwhile, have signed former Aston Villa and Juventus defender Olof Mellberg on a one-year deal. The 34-year-old was available on a free transfer after leaving Olympiakos.
The club said: "Olof Mellberg has succesfully completed his medical at the Jaime I de Castellon, and has signed a contract with the club for the next season."