The 23-year-old was reportedly close to joining Sevilla but the Giallorossi look set to gazump the Spaniards with a better financial package to take the player on loan
The Paraguayan right-back was believed to be close to a move to Sevilla but as negotiations reached an impasse the Giallorossi made a better offer than the Spanish side for his services.
"Unfortunately football is like this, you have to say yes to someone and no to someone else but I would be very happy if everything was agreed with Roma," Piris told Paraguayan radio station Futgol3D.
"I spoke with [agent] Pedro Aldave on Sunday and he told me that he has met with the Roma directors.
"It was all finalised with Sevilla but now, from what I understand, Roma are the team closest to signing me.
"A player dreams that these opportunities arise - now it is almost a reality. I have to make the most of it and do even better than I did at Sao Paulo."
Should Piris complete his move to the Italian capital he will become the fifth player to join from the Brazilian league this summer.