Boca Juniors and Corinthians clinched their places in the semi-finals of the Copa Libertadores as decisive goals were scored in the closing minutes of their matches on Wednesday.
Boca, 1-0 winners of the home leg in Buenos Aires, suffered an early setback as Fluminense scored through Thiago Carleto.
His powerful free-kick bounced off Diego Rivero and confused keeper Agustin Orion who conceded the goal which levelled the tie on aggregate.
With penalties looking likely at the Engenheiro Beltrao stadium Juan Roman Riquelme set up Rivero whose shot hit the right post before the ball was cleared.
However, the ball fell to Santiago Silva who scored the equaliser which secured a 2-1 aggregate win for Boca.
Fluminense coach Abel Braga said: "It was incredible. Our keeper had a very quiet night, they only attacked one time and it was a goal."
Riquelme said: "It was a very even match, very similar to the one we played in La Bombonera. The truth is that Fluminense found a goal with some luck. In the only time we did three consecutive passes, we scored. It was crucial, because we gave a big step to reach the final."
Corinthians had to wait until the 88th minute to beat compatriots Vasco da Gama at home.
With the sides drawing 0-0 in the first leg Corinthians tested Vasco keeper Fernando Prass on several occasions, with Emerson and Danilo also hitting the post.
For Vasco veteran Juninho Pernambucano's free-kick just cleared the bar and then Diego Souza was one-on-one with Cassio but hit his lob too close to the keeper who was able to save.
Paulinho settled the tie with a header from an Alex corner.
"This qualification was the merit of the entire team, and I think it was well deserved," said Paulinho. "Now, we have to rest and start thinking of our next rivals."