Marques was banned for three games and Alvez for one match for indiscretions during Barcelona's 1-0 victory over Santos in their quarterfinal second leg last month, reports Xinhua news agency.
Gremio, meanwhile, are expected to be boosted by the return of Brazil international forward Luan for the match at Barcelona's Monumental stadium on October 25.
The 24 year-old, who has not played for more than a month due to a right hamstring tear, has resumed training and is expected to play for Gremio against Corinthians in Brazil's Serie A championship on Wednesday.
Gremio are bidding for their third Copa Libertadores title while Barcelona are aiming to win South America's top club competition for a first time.
Argentine rivals River Plate and Lanus will meet in the other semifinal.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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