After a promising start to the season, 3 de Febrero have gone winless in seven - including five straight losses - the most recent of which seeing them ship 18 goals in their losing streak.
The visitors to the Estadio Don Eduardo Acosta Caballero were their own worst enemy, as an own goal to Felipe in the 22nd minute put Rubio Nu ahead.
Claudio Correa doubled their advantage nine minutes later, although 3 de Febrero got back in the contest on 34 minutes when David Mendieta scored.
However, Rubio Nu quickly put the game beyond 3 de Febrero's reach, with Jorge Ortega reinstating their two-goal buffer prior to half-time and additional goals to Diego Figueredo and Victor Gomez in the second half sealing the three points.
Top two clubs Libertad and Guarani were both beaten at the weekend, to preserve the former's six-point advantage in the table.
Libertad fell to a 2-1 loss to Olimpia, who remained in third - seven points behind the leaders.
Guarani were embarrassed 4-0 at home to Nacional Asuncion, who stayed level on points with Olimpia.
Sol de America also had a big win on the road, cruising to a 3-1 win at Sportivo Luqueno for their first triumph in five matches.
Deportivo Capiata and 12 de Octubre did neither of their poor predicaments any good, as they played out a 2-2 draw to keep them in the bottom three.
General Diaz sit just above those sides in ninth spot, after being held to a 1-1 draw at home to Cerro Porteno.
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