The clash pitting first against third was shaping to be a comfortable win for the hosts at the Estadio General Pablo Rojas in Asuncion after just eight minutes.
Julio Dos Santos put Cerro Porteno ahead in the second minute, with an easy finish after some calamitous defending.
And Libertad's deficit was exacerbated when midfielder Claudio Vargas was sent off six minutes later.
But Pedro Sarabia's men provided a stunning resistance, as two goals 15 minutes apart to Nestor Camacho gave them an unlikely lead.
Diego Godoy squared the match five minutes prior to half-time, smashing home into the roof of the net from an acute angle, but 10-man Libertad managed to hold on for a point crucial to their title hopes.
Cerro (26 points) remain one point clear on top of the table, after Guarani (25) were held to a 2-2 draw away at Sportivo Luqueno.
Fernando Fernandez gave Guarani a fourth-minute lead with his 11th league goal of the campaign, but Luqueno would take the lead 11 minutes from time after goals to Marcelo Ferreira and Rodrigo Teixeira.
Ivan Gonzalez rescued a point for Guarani, who remain four points clear of third-placed Libertad.
The only two winners on the weekend came from the bottom half of the table, with seventh side General Diaz and ninth-placed 12 de Octubre saluting.
Olimpia's recent woes continues, as they slumped to their third loss in four as 12 de Octubre posted a 2-1 victory.
Gustavo Santacruz scored twice for 12 de Octubre, the Paraguayan striker's third brace of the season.
General Diaz enjoyed a 1-0 win over 3 de Febrero, with Alberto Contrera scoring in the first minute after half-time.
Deportivo Capiata snapped a four-match losing streak, coming from behind to earn a 1-1 draw away to cellar-dwellers Sol de America.
Sol missed the chance to claim their third win, which would have seen them usurp Deportivo and Rubio Nu - the latter having their trip to Nacional Asuncion postponed.
