Adrian Lopez joined Porto from Atletico Madrid on Saturday, linking up with the Primeira Liga club on their pre-season trip to Netherlands.
Atletico confirmed on their website that Adrian had passed a medical with Porto, allowing the 26-year-old striker to fly with the Portuguese outfit to Eindhoven.
The medical was the final hurdle for Adrian before his transfer from Atletico to Porto would be approved.
"Atletico de Madrid and Porto have reached an agreement for the transfer of Adrian Lopez to the Portuguese club," a statement on Atletico's website read.
"The striker from Asturias leaves for the team directed by the Spanish [coach] Julen Lopetegui."
Earlier, Porto had confirmed on their website that Adrian was part of their 24-man squad for the Dutch tour, posting photos of the forward in club gear, although they did not release any details of a transfer or confirm that one had occurred.
Porto, under new coach Julen Lopetegui, are looking to bounce back in the coming season, after missing out on silverware in 2013/14.
Adrian struggled for regular game time at Atletico last season, as Diego Simeone led them to a breakthrough La Liga title, with the striker starting just four league matches behind regulars Diego Costa, David Villa and Raul Garcia.
In three seasons with Atletico, Adrian scored 26 goals in 143 appearances in all competitions, having joined the capital club from Deportivo La Coruna at the start of the 2011/12 campaign.
With Villa already on his way to expansion franchise New York City in the MLS and Chelsea already agreeing to sign Costa, Adrian's exit to Porto will leave Simeone with a large hole to fill up forward as he looks to defend their Spanish crown.
Croatia striker Mario Mandzukic has already arrived from Bayern Munich during the transfer window.
|Vardy relishing Fleetwood return|
|Almiron blocked from becoming Las Palmas coach|
|Ligue 1 adopts VAR from next season|
|Calabria extends AC Milan contract|
|Everton give new deals to Calvert-Lewin, Holgate & Kenny|
|Under-fire Hughes promises results will come for Stoke|
|Mourinho asked to explain pre-Manchester derby comments|
|Stoger sets Dortmund end of year target|
|Dyche: No swaggering from high-flying Burnley|
|Watzke plays down Nagelsmann rumour as Dortmund plan for 2018|
|Guardiola´s record runs with Manchester City, Bayern Munich and Barcelona compared|
|Benteke goal drought a concern for Hodgson|
|City look frightening – Rose|
|Kahn regrets rejecting Manchester United|
|Bayern wrapping up Ribery for Christmas|
|Wilshere no closer to signing fresh Arsenal contract|
|Resurgent Rooney has Europe´s best shot-conversion record|
|Pastore bullish over PSG chances against Madrid|
|Independiente boss overjoyed by ´dream´ Copa Sudamericana success|
|Silva is an animal - Guardiola|
|Wenger not blaming Sanchez for Arsenal´s goal woes|
|Mourinho can´t find room for misfiring Mkhitaryan|
|Guardiola tells fans Man City won´t stop after record-breaking win|
|Mirabelli: Donnarumma has to beg Milan if he wants to leave|
|Bayern lacked verve, says Heynckes|
|Di Maria wants more game time at PSG after goalscoring display|
|Gattuso: Donnarumma shaken by abuse from AC Milan fans|
|Pellegrino calls for Southampton reaction|
|Benitez ´needs to know´ extent of Newcastle´s transfer budget|
|Zidane will not request striker signing despite Benzema blanks|
|Bournemouth excellent in Old Trafford loss – Howe|
|Wilshere´s performance ´very positive´, says Wenger|
|Pochettino challenges Spurs to keep top-four berth|
|I´d be in Brazil if the title race was over – Mourinho|
|It was hard to watch - Clement wowed by City´s dominance of Swansea|
|Bailly may require surgery on ´serious´ ankle injury|
|Klopp uncertain on Solanke´s disallowed goal|
|Guardiola sure record-breaking City won´t get complacent|
|Puel focuses on Leicester win, not Southampton revenge|
|Strasbourg 2 Paris Saint-Germain 4: Revenge is sweet for Emery´s men|
|Tottenham 2 Brighton and Hove Albion 0: Aurier scores a fluke as Spurs go fourth|
|West Ham 0 Arsenal 0: Wasteful Gunners drop points for third game in a row|
|Liverpool 0 West Brom 0: More frustration for Klopp as hosts draw again|
|Manchester United 1 Bournemouth 0: Lukaku eases scoring concerns after derby day woes|
|AC Milan 3 Verona 0: Bonaventura shines as Gattuso´s side march on|
|Newcastle United 0 Everton 1: Rooney haunts Magpies again|
|Manchester City set new Premier League winning streak|
|Swansea City 0 Manchester City 4: Silva sparkles as Guardiola´s record-breakers march on|
|Southampton 1 Leicester City 4: Puel serves up Saints revenge|
|Bayern Munich 1 Cologne 0: Lewandowski opens nine-point gap in Bundesliga|
|Mourinho slams Manchester derby penalty decision in programme notes|
|This is my last season at Monaco – Fabinho|
|Bale: Football would be better without VAR|
|Thought Mayweather v McGregor was 2017´s biggest sporting event? Think again!|
|Manchester United´s Gomes pens professional contract|
|Al Jazira 1 Real Madrid 2: Bale spares Spanish blushes at Club World Cup|
|Ronaldo takes goalscoring record from Messi|
|Al Jazira stun Real Madrid to take half-time lead in Club World Cup|
|Neymar returns to PSG after break|
|Iniesta would welcome Barca pursuit of Coutinho|
|FA extends deadline for Manchester clubs to respond over alleged derby fracas|
|Dybala clever enough to listen to Nedved - Buffon|
|Willian not ready to walk out on Chelsea|
|Arsenal striker Lacazette not counting on title miracle|
|World Cup glory worth €350,000 to Germany stars|
|I live day by day - Buffon ponders Euro 2020|
|West Ham eyeing Wilshere swoop in January|
|Klopp reveals hamstring scare for Liverpool star Salah|
|FFA refuses to speculate on Scolari amid Socceroos interest|
|Ronaldo hoping to play with Benzema and Bale again|
|Mourinho takes aim at reporters as Man United boss leaves news conference|
|´Bull****´ to suggest Chelsea can catch Man City – Conte|
|Pordenone would´ve deserved Coppa Italia progression, admits Spalletti|
|Man City haven´t won anything yet – Gundogan|
|Willian: Chelsea will keep fighting for Premier League title|
|Burnley aren´t the real deal – Dyche|
|Stoger wants to bring best out of BVB after breakthrough victory|
|Conte praises contribution of Hazard, Willian and Pedro|
|Inter 0 Pordenone 0 (AET, 5-4 on penalties): Nagatomo spares Serie A leaders´ blushes|