Angel Romero's early brace, a header from Junior Alonso and Julio dos Santos' late penalty saw Cerro Porteno destroy Pedro Sarabia's recently crowned champions, who had claimed the league title last week following a 0-0 draw with Deportivo Capiata.
The victory took Cerro Porteno into fifth in the table with 24 points, ahead of Nacional Asuncion on goal difference, while Libertad remained on 36 points but cannot be overhauled by second-placed Guarani, who crushed Rubio Nu 4-1 to reach 30.
The 21-year-old forward showed impressive control for his first goal in the 18th minute, bringing down a high ball in the box, before cutting inside his marker to score, while Romero's second seven minutes later came after Libertad's goalkeeper parried another shot into the youngster's path.
It was 3-0 four minutes into the second half when Alonso nodded a free-kick home from close range, while dos Santos converted a penalty in the 88th minute to complete Porteno's victory.
Francisco Gomez gave the hosts the lead in the 18th minute but Guarani stormed back in the second half with Rafael Benitez scoring the equaliser just before the hour mark before Julio Caceres, Fernando Fernandez and Marcelo Palau completed the visitors' triumph.
