BUENOS AIRES, Sept. 19 (Xinhua) -- Defending champions Gremio took a step towards earning a place in the Copa Libertadores semifinals with a 2-0 victory over 10-man Atletico Tucuman of Argentina on Tuesday.

Alisson put the Brazilian side ahead with a 35th-minute strike and the visitors were handed a further advantage when Atletico midfielder Gervasio Nunez was sent off on the stroke of halftime.

Gremio then doubled their lead just before the hour mark thanks to a goal from Brazil international forward Everton after he was set up by Alisson.

The second quarterfinal leg will be played at Gremio Arena in the southern Brazilian city of Porto Alegre on October 2.

In Wednesday's quarterfinals, Argentina's Independiente will host local rivals River Plate and six-time champions Boca Juniors, also of Argentina, are at home to Brazilian side Cruzeiro.