Vasco da Gama and Corinthians played cautiously under pouring rain at the Sao Januario stadium and will decide a place in the semifinals in next week's second leg in Sao Paulo.

Alecsandro scored with a header in the 71st, but the goal was disallowed because the Vasco forward was ruled offside.

It was a matchup between Brazil's most successful teams last year. Corinthians won the Brazilian league and Vasco captured the Brazilian Cup. Vasco da Gama also was runner-up to Corinthians in the Brazilian championship.

Corinthians is Brazil's second-most popular club behind Flamengo, and the Copa Libertadores is the only major competition it is yet to win. Among its titles is FIFA's inaugural Club World Cup in 2000.

Vasco is trying to win Latin America's most important club competition for the first time since 1998.

Juninho, a member of Brazil's squad in the 2006 World Cup, had one of Vasco's scoring chances late in the first half but couldn't get a shot off after clearing two defenders inside the area. Eder Luis also came close in the 51st with a low shot saved by Corinthians goalkeeper Cassio.

Corinthians threatened with a header by Jorge Henrique in the 60th and Emerson (pictured) minutes later but Vasco goalkeeper Fernando Prass made great saves to keep the score even.

The other two quarterfinals will be played on Thursday: Vélez Sarsfield of Argentina will host defending champion Santos of Brazil in what will be a huge match up while fellow Brazilian club Fluminense will play six-time champion Boca Juniors in Argentina.