Oscar Cardozo scored in the first half and Paraguay held on for a 1-0 win over the United States on Tuesday that left the Americans winless in three games this year.
The goal started with a Hernan Perez corner kick in the 17th minute and it marked the fourth international goal for Cardozo who plays for Benfica in the Portuguese league.
Paraguay advanced to the quarter-finals of the World Cup last year. They have now won two consecutive games over the United States.
American coach Bob Bradley started 18-year-old Juan Agudelo after he scored in two of his first three international appearances, including Saturday's 1-1 draw with Argentina.
The Americans next match is June 4 against a very experienced Spanish squad. It will be their final preparation match for the CONCACAF Gold Cup.
Paraguay is competing in the Copa America event in July.