in Argentina. He was registered with the number #16 shirt and was the only player from his respective club, 12 de Octubre, to be selected in the squad. Drawn into Group F with Ghana, France and Iran, Bareiro would first appear in the tournament in Paraguay's opening fixture, a 2–1 loss against Ghana on 18 June. Bareiro was substituted onto the field in the 86th minute for Santiago Salcedo. Bareiro would miss the next fixture, a 2–2 draw with France, before being in the starting eleven and playing a full 90-minutes of Paraguay's third and final group stage fixture, a 2–0 victory against Iran on 24 June. During the match, Bareiro received a yellow card in the 64th minute. Paraguay finished in third place with 4 points, advancing to the knock-out stages as the first of six third placed teams. On 28 June, Paraguay defeated Ukraine 2–1 in their Round of 16 clash which saw Bareiro play a full 90-minutes of the fixture. Bareiro would again be in the starting line up and play out the entire match of Paraguay's quarter-final fixture, a 1–0 victory over Czech Republic on 1 July. On 4 July, Paraguay were defeated 6–0 against hosts Argentina was Bareiro was again in the starting line up and substituted off of the field in the 81st minute for forward Cristian Fatecha. On 8 July, Paraguay concluded the tournament being defeated 1–0 against Egypt in the Third place play-off, as Bareiro played a full 90-minutes of the fixture, receiving his second yellow card of the competition in the 58th minute. Paraguay U23 2004 CONMEBOL Men Pre-Olympic Tournament In 2004, Bareiro was selected for Paraguay's U23 squad to participate at the 2004 CONMEBOL Men Pre-Olympic Tournament held in January in Chile. He joined an all under-23 squad contained with domestic footballers in Paraguay's Primera División. Paraguay, being drawn into Group A with hosts Chile, alongside Brazil, Uruguay and Venezuela, had earned 3 points out of three matches, sitting in third place, and would face Uruguay in their last fixture, who were in fourth position with 2 points, as Paraguay needed at least one point to advance to the next round. On 15 January, the final group stage fixture was played which saw the two teams tied at 1–1 until the 85th minute which was when Bareiro netted the winner to give Paraguay the lead and 3 points in order