Libertad were held to a scoreless draw by lowly Deportivo Capiata, to see their lead in Paraguay's Division Profesional cut to nine points.
Pedro Sarabia's side entered the fixture at their Estadio Dr Nicolas Leoz home having scored 35 goals in 14 matches this season, but were held goalless for the second time in the campaign as Capiata earned a valuable point.
Libertad are still well clear at the helm of Paraguay's top flight on 36 points, with Guarani (27) their closest challenger.
Guarani beat Sportivo Luqueno 1-0 courtesy of Jorge Benitez's 34th-minute goal, as they held onto second spot despite wins to Olimpia (third, 26) and Nacional Asuncion (fourth, 23).
Olimpia trounced Rubio Nu 3-0 at home, despite playing most of the second half with 10 men.
Neri Cardozo struck either side of Derlis Gonzalez's goal, to cap a nine-minute bonanza in the first half from Olimpia.
Nacional Asuncion were 2-1 winners at home to Cerro Porteno, to move into the top four.
Sol de America fell to fifth, after being held to a 1-1 draw at home to cellar-dwellers 12 de Octubre.
General Diaz twice pegged back 3 de Febrero, but the latter emerged with a 3-2 road win for just their second success of the campaign.