Second-half strikes from Federico Santander and Ivan Gonzalez Ferreira saw Guarani continue their winning streak on Sunday, while league leaders Cerro Porteno made it 14 games unbeaten with a 2-1 win over General Diaz.
In Asuncion, Guarani and Olimpia were fairly even in terms of possession and attempts on goal but the home side blew the game open in four second-half minutes at the Estadio Defensores del Chaco.
Santander opened the scoring in the 61st minute, making a diagonal run into the box, touching the ball past Olimpia goalkeeper Victor Centurion and then poking his shot into the net with the outside of his right boot.
In the 63rd minute, Derlis Gonzalez collected a long pass into the left channel, twisted and turned past his opponent and then unleashed a shot Centurion could only parry into the path of Ferreira, who slotted the ball into the net for a 2-0 lead.
Guarani remain sixth on the table but moved within three points of third-placed General Diaz (26 points).
Cerro Porteno had to come from behind to knock off General Diaz, who lost their fourth straight match in Paraguay's top flight.
Antonio Barreiro gave General Diaz the lead at Cerro Porteno's Estadio General Pablo Rojas in the 25th minute but the home side equalised before the break through Guillermo Beltran.
Jose Maria Ortigoza struck the winner for Cerro Porteno with 20 minutes left on Saturday - a result which sees them nine points clear at the top of the standings with 40 points.
General Diaz's loss allowed Deportivo Capiata to strengthen their hold on second position as they defeated Deportivo Carapegua 3-1.
Deportivo Capiata have 31 points after 16 rounds, while General Diaz have 26 and are just ahead of fourth-placed Nacional Asuncion on goal difference.
Nacional were held to a scoreless draw by Sportivo Luqueno, while Rubio Nu defeated Sol de America 2-1 and Libertad overcame Cerro Porteno PF 1-0.
