Having gone into the Asuncion derby at the national Defensores del Chaco stadium two points behind Olimpia in second place, Cerro Porteno had Uruguayan Walter Lopez sent off in the eighth minute for elbowing an opponent.
Numerical parity was restored within ten minutes when Olimpia, last year's Clausura champions, had Peruvian Renzo Revoredo shown a straight red card for a dangerous challenge.
Striker Santiago Salcedo, with a 36th minute penalty, and midfielder Jonathan Fabbro, with a free kick in the 65th, gave Cerro Porteno a two-goal lead.
Olimpia had midfielder Eduardo Aranda dismissed in the 68th for a second booking but they managed a consolation goal through substitute Arnaldo Castorino 15 minutes from time setting up a nail-biting finale.
Lowly Carapequa had three players sent off during their 1-0 defeat away to fourth-placed Sol de America.
Defenders Diego Cantero and Ruben Maldonado were dismissed in the second half, and substitute Diego Benitez was also shown the red card for protesting from the bench.