Paraguayan giants Cerro Porteno claimed a 1-0 home win over Deportivo Petare of Venezuela and made an important step towards the Copa Libertadores group stage.
Roberto Nanni earned Cerro the win with a second half goal in the first leg of the first stage and now they are flying to Venezuela for the return match next Thursday with a small advantage.
Argentinian-born striker Nanni headed in a Lautaro Formica cross to the edge of the six-yard box to net the winner in the 69th minute.
Javier Torrente's Cerro Porteno will have to improve their finishing as Deportivo Petare keeper Alan Liebeskind was the man of the match at the Estadio Defensores del Chaco.
In La Paz, Union Espanola of Chile did not show any effects of playing at 3,600 metres above the sea level and defeated Bolivian giants Bolivar 1-0.
Fernando Cordero headed a Leonardo Monje cross home in the 15th minute to give Jose Luis Sierra's side a crucial win ahead of the second leg next Thursday.
Bolivar defender Ze Carlos was sent off with 10 minutes to go at the Estadio Hernando Siles.