BUENOS AIRES, Oct. 23 (Xinhua) -- Midfielder Michel Ferreira struck a second-half goal as Brazil's Gremio took a step towards the Copa Libertadores final with a 1-0 victory over River Plate of Argentina on Tuesday.

After a goalless first half, Gremio broke the hosts' resistance just after the hour mark when Ferreira met an Alisson Euler corner with a powerful header at the near post.

Despite enjoying more than two thirds of ball possession, River rarely troubled Gremio's defense. Their best chance came in the 31st minute when a long-range Exequiel Palacio shot forced a diving save from Marcelo Grohe.

The result at the Monumental stadium means that Gremio need only a draw in next week's return fixture in Porto Alegre to progress to the final.

"It's a small advantage but we know they are a big team and next week's game is going to be even tougher," Grohe said after the match. "We are going to have to prepare for the game as best as we can and stay focused for the full 90 minutes."

Gremio are aiming to become the first team since Argentine giants Boca Juniors in 2000 and 2001 to win back-to-back Libertadores titles.

On Wednesday, Boca will host Brazil's Palmeiras in the other semifinal first leg.

The winners of the Copa Libertadores - South America's top club competition - will earn a berth in the FIFA Club World Cup in the United Arab Emirates in December.