Luan is nursing a foot injury while Everton is struggling to recover from a thigh problem that forced him out of Brazil's international friendlies against Saudi Arabia and Argentina earlier this month.

Gremio could also be without veteran right-back Leo Moura, who has a calf complaint.

Wednesday's clash at the Bombonera features two teams that have had vastly different fortunes in the Copa Libertadores.

Palmeiras, the most successful club in Brazil's Serie A history with nine titles, have won just one Copa Libertadores title: in 1999 during Scolari's first spell as coach. They were losing finalists to Boca Juniors the following year but have mostly struggled in the competition since then.

Boca, meanwhile, are six-time Copa Libertadores champions and could this year equal Independiente's record as the club with the most titles.

Palmeiras have been rejuvenated under Scolari, who returned to coach the club for a third time in late July. Since then the Sao Paulo outfit have won 16 and lost just two of their 23 matches in all competitions and they currently hold a four-point buffer at the top of Brazil's Serie A standings.

Conversely, Boca have struggled to recapture the form that saw them win the past two Superliga Argentina titles. Guillermo Barros Schelotto's men are currently fifth in the Superliga standings with just four wins from nine matches this season.?

【体坛英语资讯：Copa Libertadores preview: Argentina and Brazil clash in semifinals】相关文章：

★ 体坛英语资讯：Germany beats North Korea 3-0 to advance to semifinals

★ 娱乐英语资讯：Angelina Jolie in French hospital to give birth

★ 娱乐英语资讯：Mel B enlists Posh to design sexy frocks

★ 体坛英语资讯：Kansas tops Memphis to clinch first NCAA title

★ 体坛英语资讯：China wins womens team title at table tennis worlds

★ 娱乐英语资讯：Pink and racer hubby Carey Hart split up

★ 娱乐英语资讯：My China Now short films unveiled in London gallery

★ 体坛英语资讯：Zheng makes history with semis spot in grand slam

★ 娱乐英语资讯：Madonna link? Report says Rodriguez, wife split up

★ 体坛英语资讯：Stephen Maguire triumphs in China Open