Porto have continued their intensive summer of rebuilding with the signing of left-back Jose Angel on a free transfer.
The 24-year-old, who has spent the last two seasons on loan at Real Sociedad from Roma, has signed a four-year deal.
Porto also confirmed via a statement on their website that the Spaniard has a 30 million-euro release clause.
"It is a great joy to be here,'' he told the club's official website. "For me it is a huge challenge, because I think it is a great club that is creating a good group. It is important to have a good team and good players. Porto is making good hires.
"What is a good year for sure, doing things right, we will be fighting for important things. I have high expectations and can not wait to start training and be 100 percent. ''
Porto are wasting no time in the summer transfer window as they bid to rebuild heavily in order to make amends for a disappointing third-placed finish in the 2013-14 Primeira Liga table.
Adrian and Oliver Torres have arrived from Atletico Madrid, Cristian Tello and Casemiro have left Barcelona and Real Madrid respectively to move to Portugal, while Netherlands left-back Bruno Martins Indi and Ghana right-back Daniel Opare have also been added to coach Julen Lopetegui's new-look squad along with Granada midfielder Yacine Brahimi.
Juan Iturbe, Fernando, Andre Castro, Sinan Bolat, Marat Izmailov and Jorge Fucile have all left the club.