Evaristo Piza's men were 2-0 winners at 3 de Febrero thanks to a brace from Jorge Benitez on Sunday, while Libertad played out a 1-1 draw with Nacional Asuncion on Monday.
Libertad's (44 points, +22) second consecutive stalemate has seen their lead in the Apertura campaign cut to four points by Guarani (40 points, +19) with two rounds remaining.
Guarani travelled to the Estadio Antonio Aranda in the midst of a seven-game unbeaten run, with last week's 2-1 success at home to 12 de Octubre their most recent success.
And they put themselves on track to continue that good form when Benitez opened the scoring in the 14th minute - the striker's fourth goal in three games.
Benitez sealed all three points nine minutes from time as Guarani condemned second-bottom 3 de Febrero to a third consecutive defeat.
Over at the Estadio Defensores del Chaco, Marcos Prieto struck in the first minute of injury time to salvage a 1-1 draw for Nacional Asuncion against Libertad.
Libertad looked set to win after Antonio Bareiro put the visitors ahead with 16 minutes remaining but Asuncion secured a share of the spoils late on.
In other results, Sol de America climbed to third in the standings thanks to a routine 3-0 victory at home to Olimpia.
Goals from Ignacio Mino, Diego Chamorro and Diego Vazquez saw Sol de America (30 points, +7) rise above Olimpia (30 points, +7) on goal difference, though their opponents have a game in hand.
Olimpia are set to play seventh-placed Cerro Porteno in their rescheduled round 17 clash on Wednesday.
Cerro Porteno will be seeking an improvement ahead of their midweek fixture after they were beaten 4-1 by Rubio Nu on Saturday.
Elsewhere, cellar-dwellers 12 de Octubre earned an unlikely 1-1 draw at home to Sportivo Luqueno, while Deportivo Capiata edged General Diaz 1-0
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