A first-half goal from Marco Ruben saw Rosario Central claim a 1-0 win away to Gremio in the first leg of their Copa Libertadores round-of-16 tie.
Rosario started the game brightly at Arena do Gremio on Wednesday and the Argentine side took the lead in the 14th minute thanks to Ruben's fifth goal of the competition.
The former Villarreal forward smashed home from close range after the Gremio defence failed to deal with a bouncing ball in the box.
Rosario managed to weather a late storm from their Brazilian opponents, holding on to take a 1-0 advantage with the vital away goal into next week's return leg.
Corinthians, the 2012 winners of the competition, were able to secure a good result after holding Nacional to a scoreless draw at Gran Parque Central.
The Brazilian side did not do much attacking, happy to sit back and let Nacional control the game in front of the Uruguayan crowd.
The tactic worked to full effect, leaving the tie wide open for the return leg in Sao Paulo.
Meanwhile, Racing Club and Atletico Mineiro also played out a 0-0 stalemate in their first-leg clash.
Leandro Grimi thought he gave the home side the lead in the first half but his effort was ruled out for offside in a marginal call.
Former Lyon and Porto striker Lisandro Lopez rattled the crossbar in the second period but the Argentine side were unable to break down their Brazilian opponents.