A goal three minutes before the 90 last week enabled Flu to come away with a 1-1 draw versus El Bicho, the first positive result for the Brazilians away from home in this competition since a 3-1 victory on matchday one versus Sporting Cristal.
Match preview
Throughout this competition, Fluzao have started slowly on the road, conceding the opener each time, though they were able to pick themselves back up and find an answer in the nick of time last Tuesday.
That draw will feel like a win for Fernando Diniz's men, who had lost seven of their previous eight away matches in all competitions before facing Argentinos, failing to score in each of those defeats.
Their form at home has been a much different story, with the reigning champions of the Taca Guanabara and Campeonato Carioca unbeaten at the Maracana since late January.
They have, however, never beaten Argentinos at home in this competition, losing 1-0 to them in the 1985 group stage and playing to a 2-2 draw in 2011.
Fluzao have only conceded two goals in their last five home matches played in all competitions, but they have won four of five return legs in the last 16 of the Libertadores this century.
In the opening phase of this competition, Fluminense only conceded once in three home fixtures and have not given up more than one goal in a single match at the Maracana all year.
For the second time in the last three years, Argentinos enter this deciding match tied at one with an opportunity to advance into the quarter-finals for the first time in the 2000s.
Although conceding so late was disappointing, lately the Argentines have looked more than comfortable away from home, currently unbeaten in three successive road matches in all competitions while winning at Corinthians in the group stage of this tournament (1-0).
In addition to that, this team have fared well in Brazil at the Libertadores, unbeaten in four away fixtures against Brasileiro Serie A sides in this competition, including a pair of clean sheets.
Gabriel Milito's men have only conceded one goal in the opening half of their last seven competitive matches played away from home, posting a clean sheet in their previous two domestic road outings.
Argentinos have not lost a competitive away fixture when leading at the interval since February, when River Plate converted two second-half penalties for a 2-1 triumph.
Over the past two knockout stage ties at the Libertadores, only one team from the Argentine Primera Division have been able to take out a Brazilian side, with Estudiantes advancing past Fortaleza in the last 16 last year 4-1 on aggregate.
Fluminense Copa Libertadores form:
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Fluminense form (all competitions):
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Argentinos Juniors Copa Libertadores form:
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Argentinos Juniors form (all competitions):
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Team News
On Tuesday, Flu will be without Marcelo after he was red-carded in the second half of their opening leg, while Alexsander is unavailable until mid-September because of a thigh injury.
An 87th-minute strike by Samuel Xavier rescued the Brazilians last week, his first of this competition, while German Cano failed to score in a third successive Libertadores away fixture, though he has four at home in this year's competition.
Jhon Arias and John Kennedy found the back of the net for them over the weekend as Fluminense edged the reigning Brasileiro Serie A champions Palmeiras 2-1.
Federico Lanzillota could reclaim his place between the sticks for Argentinos on Tuesday after Alexis Martin Arias was sent off late in the second half last Tuesday, Facundo Ferreyra sat out of that match due to a calf strain, while Luciano Sanchez was unavailable because of a dislocated kneecap.
Gabriel Avalos had the opening goal for El Bicho last week, his first of the competition, while Leonardo Heredia saw his two-game scoring streak at the Libertadores come to an end as he failed to make an impact after coming on for Luciano Gondou for the final 16 minutes plus stoppage time.
Avalos and Gaston Veron both netted in their previous away victory when they defeated Patronato 2-1 in the round of 32 at the Copa Argentina.
Fluminense possible starting lineup:
Fabio; Xavier, Nino, Melo, Jorge; Ganso, Andre, Martinelli; Arias, Cano, Alan
Argentinos Juniors possible starting lineup:
Lanzillota; Sanchez, Di Cesare, Villalba; Cabrera, Redondo, Moyano, Heredia; Nuss, Avalos; Veron
We say: Fluminense 2-0 Argentinos Juniors
Playing in a game of this magnitude is foreign territory for many of these Argentinos players, and the Maracana has proven to be a massive advantage for Fluminense, who have plenty of recent experience to draw upon in these continental competitions, which should come in handy.