Duilio Beretta Avalos (Spanish pronunciation: [ˈdwiljo βeˈɾeta aˈβalos]; born February 25, 1992) is a Peruvian professional tennis player. He won the finals stage of Boys' Doubles events on the French Open and US Open with Ecuadorian tennis player Roberto Quiroz in 2010. They defeated Argentinian pair Facundo Argüello and Agustín Velotti in France and won against Oliver Golding and Jiří Veselý in the United States.