Born in Itauguà, Paraguay, but with dual Italian nationality, Piris began his professional career in 2008 at one of  the country's biggest clubs, Cerro Porteno. He made 27 league appearances and scored 1 goal in his first three seasons but it was in the 2010 and 2011 editions of the Copa Libertadores that he really caught the eye, excelling in particular (14 appearances and 1 goal) during his team's impressive run in 2011, when their final hopes were dashed by Santos. That made European clubs sit up and take notice but it was São Paolo who won his signature. Piris continued to live up to expectations in Brazil, clocking up 17 appearances and 1 goal in his first Brazilian campaign, before making 3 appearances in 2012 against Bahia, Internacional and Santos. Pacy and strong despite his slight figure (174 cm, 68 kg), like most South American full-backs he gives the best of himself when going forward. He was a member of the Brazil team that took part in the U-20 World Cup in 2009 and made his senior debut with the Seleção against Ecuador in the 2011 Copa America.

Cerro Porteno
Piris spent 3 years at the Paraguayan giants, playing a particularly large role in Cerro Porteno's run to the semi-finals of the 2011 Copa Libertadores. However, his impressive performance in the competition alerted clubs around the world of his ability and it looked unlikely that he would stay with Cerro Porteno. Piris eventually signed for Brazilian club São Paulo FC for a fee of alleged €2 million. However, São Paulo bought a portion of economic rights on Piris and the registration rights was held by a proxy club Deportivo Maldonado, the entity to receive transfer fee. São Paulo signed Piris in a 2-year loan deal on 19 July 2011.

São Paulo
Piris joined up with his new team-mates after the 2011 Copa America after São Paulo announced his signing on Thursday 15 July  São Paulo's vice-president spoke of his delight at signing Piris: "For months we have been working quietly on this player and to see it succeed makes us very happy", he told the club's official website. "Piris is a young athlete who has lots of potential. He will definitely add great quality to our group."

Roma
On 1 August 2012, Piris was loaned to Italian side Roma for a fee of €0.7 million, with the option of purchasing his rights at the end of the 2012/13 season for €4 million.