It is the first time since 2021 that both of these sides are in the last 16 of this tournament, as the Argentines finished second in their group with 11 points, while Fluzao ended up first in their group, ahead of River Plate on goal difference despite going winless in their final three group stage affairs.
Match preview
After putting together some solid performances in the group stage, Argentinos can do something this club have not managed to do in the 2000s, win a knockout fixture at the Copa Libertadores.
Gabriel Milito had a great defensive game plan in the group stage which his players executed to near perfection at home, conceding only once in their three matches played in La Paternal, where seven of their 11 points were secured.
El Bicho are coming off an impressive month of July, in which they lost just two of their seven competitive fixtures, while posting four clean sheets.
A six-match unbeaten run for them at Estadio Diego Armando Maradona ended over the weekend when they suffered a 3-2 defeat versus Estudiantes, conceding as many goals in that one game than they had in their previous seven home matches combined in all competitions.
In the Libertadores group phase this year, Argentinos went unbeaten in both group matches played against Corinthians, keeping them off the scoresheet each time and winning one of those encounters, the first victory for them versus a Brazilian opponent in this competition since 2008, which was also the last time Juniors eliminated a Brasileiro Serie A opponent in the knockout stage of this tournament (3-0 quarter-final aggregate win over Palmeiras).
In the group stage, this team only allowed one goal in the opening 45 minutes of play, while they have only conceded one first-half strike at home in their last eight matches in all competitions.
Over a year since they exited this tournament in the third qualifying round, Fluminense were able to put themselves in a much better position this time around, winning their opening three group fixtures by a combined score of 9-2.
It is a good thing they got off to such a hot start because their form in the second half of the group phase was anything but sizzling, with just one point from their final three encounters, netting only once over that stretch.
Fernando Diniz, who will be pulling double-duty for the next year as both the Fluminense manager and the interim boss for the Brazilian national team, saw his club end a two-match winless and goalless run in league play this past weekend by defeating Santos 1-0.
The away record of Fluzao throughout the campaign has often held them back, and they enter this match on Tuesday without a road victory in eight successive games in all competitions, failing to score in seven of those outings.
Fluminense have not tasted defeat in a Libertadores knockout stage encounter since squandering a 1-0 lead at Olimpia in the 2013 quarter-finals, losing that second leg encounter 2-1 as the Brazilians were eliminated on aggregate by that very margin.
Tuesday will be the fifth time Fluzao take on Argentinos at the Copa Libertadores, and in the previous four matchups against them, the club from Rio have only triumphed once, earning a 4-2 road victory at El Bicho in 2011.
Argentinos Juniors Copa Libertadores form:
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W
D
D
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L
Argentinos Juniors form (all competitions):
L
D
D
W
W
L
Fluminense Copa Libertadores form:
W
W
W
L
L
D
Fluminense form (all competitions):
D
L
W
D
L
W
Team News
Juniors will be without Fabricio Dominguez and Santiago Montiel for this opening leg, having both been red-carded on matchday six of the group stage, Facundo Ferreyra might be available despite previously straining his calf, while Franco Moyano is likely a few weeks away from a return following his muscle injury.
Gabriel Avalos is second in the Argentine Primer Division with 12 goals but did not find the back of the net in the group stage of this tournament, as Javier Cabrera and Leonardo Heredia both had a pair of strikes in the opening six games to lead the team.
Federico Lanzillota had two clean sheets in their opening three group fixtures at the Libertadores before Alexis Martin Arias took his place, conceding four goals in his three matches played between the sticks.
Alexsander is not expected to return to the Fluminense lineup until early September because of a thigh injury, Jorge is doubtful with a cruciate ligament rupture and Vitor Mendes remains on special leave.
German Cano is the second-highest scored at this competition with six goals, one fewer than Paulinho of Atletico Mineiro for the lead, while Jhon Arias notched the most for them in the group stage (two).
Fabio is tied for third in the Brasileiro Serie A this season regarding clean sheets (six), though he only has one at the Libertadores this year, stopping two shots in a 1-0 victory over The Strongest back in April.
Argentinos Juniors possible starting lineup:
Arias; Sanchez, Mac Allister, Torren, Gonzalez; Redondo, Moyano; Heredia, Metilli, Veron; Nuss
Fluminense possible starting lineup:
Fabio; Xavier, Nino, Melo, Marcelo; Martinelli, Andre; Arias, Ganso, Keno; Cano
We say: Argentinos Juniors 1-1 Fluminense
Argentinos were the more consistent of the two sides in the group stage, but Flu have a quality finisher in Cano who does not need much of an opening to score.
This could be more of a feel-out game for these two evenly-matched sides, which is why we believe that a stalemate is a logical scoreline.