Fluminense booked a spot in the Copa Libertadores round-of-16 with a 1-0 victory over Zamora on Thursday, while Boca Juniors also won.
A 79th-minute goal from substitute Rafael Sobis helped Brazilian giants Fluminense to their fourth win in as many games in Group 4.
The 2008 runners-up are nine points clear of third-placed Arsenal de Sarandi with two games remaining, while Boca Juniors are second in the group.
Wellington Nem threatened in the early stages of the encounter in Barinas, Venezuela, and the visitors missed several chances as former Porto and Barcelona star Deco combined well with Fred.
The decision to introduce Sobis on 76 minutes paid dividends for manager Abel Braga, with the forward netting what proved to be the winner from a free-kick.
In the other Group 4 game, 10-man Boca Juniors recorded an important 2-0 win at home to fellow Argentine outfit Arsenal de Sarandi.
Boca defender Leandro Somoza was sent off after picking up his second yellow card in the 37th minute.
The hosts still managed to open the scoring five minutes after half-time when Pablo Ledesma struck.
A counter-attack led to Juan Roman Riquelme forcing a save from Arsenal goalkeeper Cristian Campestrini, and it fell into the path of Ledesma, who made it 1-0.
Juan Sanchez Mino sealed the three points late on to see Boca move four points clear of Arsenal.
