Prono qualified for the men's 100 m breaststroke at the 2008 Summer Olympics in Beijing, by clearing a FINA B-standard entry time of 1:03.35 from the Charlotte UltraSwim Prix in Charlotte, North Carolina. He challenged seven other swimmers on the third heat, including three-time Olympians Malick Fall from Senegal, and Alwin de Prins of Luxembourg. Prono edged out Fall to snatch a third spot by 0.19 of a second, breaking his personal best and Paraguayan record of 1:02.32. Prono failed to advance into the semifinals, as he placed forty-first out of 65 swimmers on the first night of the preliminaries.