A first-half goal from Marco Ruben was enough to give Rosario Central a 1-0 away victory over Gremio in their Copa Libertadores round of 16 first leg on Wednesday.

Ruben capitalized on hesitant Gremio defending by pouncing on German Herrera's chest-down before rifling the ball past goalkeeper Marcelo Grohe with an unstoppable first-time finish.

The result at Gremio Arena in Porto Alegre means the Argentine outfit need only a draw in their return match next week to advance to the quarterfinals of South America's top club competition.

In Montevideo, Brazilian giants Corinthians held three-time champions Nacional to a 0-0 draw.

And in Wednesday's only other round of 16 match, 2013 champions Atletico Mineiro of Brazil held Racing Club to a 0-0 draw in Buenos Aires.