Adrian has been closely linked with the Portuguese giants in recent days and on Saturday Porto announced that the 26-year-old Spain international had joined the squad for their pre-season training camp in Holland.
Porto said on their official Twitter account: "The team is now travelling for the Netherlands and there's a new player on the squad: @adrian7oficial! Welcome!"
Atletico subsequently announced a deal had been struck for the striker, saying in a statement on their website: "Atletico Madrid and Porto have reached an agreement for the transfer of Adrian Lopez to the Portuguese club.
"The Asturian striker leaves for the team that is coached by Spaniard Julen Lopetegui and with whom he has passed his medical.
"From the club we wish Adrian the best of luck in this new stage of his footballing career."
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