Ecuadorans Barcelona held on amidst late drama to edge out Fluminense on away goals following a 1-1 draw in Guayaquil that prevented a clean sweep of Brazilian teams from reaching the Copa Libertadores semi-finals.

Barcelona took the lead on 73 minutes through Uruguayan Gonzalo Mastriani and although veteran Fred equalized from the penalty spot eight minutes into injury time, Fluminense could not force a winner on Thursday night.

The plucky Ecuadorans progressed thanks to their 2-2 draw at Rio de Janeiro's Maracana stadium last week.

They will next face the 2019 champions and Brazilian giants Flamengo in September's two-legged semi-final.

Flamengo completed a one-sided rout of Paraguay's Olimpia as Brazil international forward Gabriel Barbosa scored twice in a 5-1 victory in Rio de Janeiro on Wednesday that completed a 9-2 aggregate success.

The other semi-final will be between reigning champions Palmeiras and Atletico Mineiro, the 2013 winners.

Palmeiras beat Sao Paulo 3-0 on Tuesday to complete a 4-1 aggregate victory while Mineiro knocked out Argentine giants River Plate, the 2018 champions, 4-0 over the two legs following a 3-0 win on Tuesday, with veteran Hulk scoring one of the goals.

The Copa's one-off final will be held in November at Montevideo's Centenario stadium -- site of the first ever World Cup final.