Clube de Todos played to a 1-1 draw in their final group fixture with Estudiantes to finish second, while the defending champions topped Group A, winning their last Libertadores encounter 3-2 over Alianza Lima.
Match preview
It was a rough beginning to the Copa Libertadores for Gremio, but to their credit, they came on strong down the stretch of the group phase, claiming points in three of their final four fixtures after losing the opening two.
Renato Gaucho's men were seven minutes away from finishing first in their group before Mauro Mendez equalised for Estudiantes, allowing Bolivian side The Strongest to claim first place on goal difference.
That was the second time the former Fluminense boss had seen his side drop points at home in this tournament, though they enter this contest without a defeat in normal time in four consecutive competitive games at Estadio Couto Pereira.
Tuesday will be their first Libertadores knockout fixture since the 2020 campaign, when they made the quarter-finals and were eliminated by fellow Brazilian side Santos 5-2 on aggregate.
Gremio have advanced beyond the last 16 in their previous four appearances at this stage, winning four consecutive home fixtures in this phase.
In their previous seven encounters with Fluminense, all in the Brasileiro Serie A, Imortal Tricolor emerged victorious each time, with every triumph being by a single goal.
Some strong second-half showings throughout the group phase propelled Fluzao to first place without a single defeat in the opening round.
Mano Menezes has seen his side outscore the opposition 7-1 in the final 45 minutes of this tournament, while they were never ahead at the interval in any of those encounters.
Fluminense are undefeated in 11 consecutive knockout matches at this tournament, with their last Libertadores defeat in the knockout phase occurring in the 2013 quarter-finals against Olimpia (2-1).
The club from Rio are on a two-match losing run away from home across all competitions, suffering a 2-0 defeat domestically at Vasco da Gama on Saturday.
Their dramatic 2-1 come-from-behind victory over Internacional in the second leg of their Libertadores semi-final tie last year was the first time since 1971 (2-0 win over Palmeiras) that they defeated a Brazilian opponent in this competition away from home.
Flu have not won an away match versus Gremio since erasing a three-goal deficit to defeat them 5-4 in a 2019 domestic encounter, while they have never beaten Imortal Tricolor or scored a goal in their two previous meetings against them in this competition.
Gremio Copa Libertadores form:
L
L
W
W
W
D
Gremio form (all competitions):
D
W
D
W
L
W
Fluminense Copa Libertadores form:
D
W
D
W
W
W
Fluminense form (all competitions):
W
W
L
W
D
L
Team News
Gremio will be without Jhonata Robert and Andre until late August due to a knee and ankle injury, respectively, while Mayk could be available despite previously suffering from muscle soreness.
One change was made to their starting 11 from matchday five to six at the Libertadores, with Cristian Pavon replacing Everton on the wing.
Franco Cristaldo netted the only goal versus Estudiantes on matchday six, the first for the Paraguayan at the Libertadores this season.
Fluzao may be missing David Terans for this opening game as he is dealing with a calf strain, while German Cano may have to sit out with a sore foot.
Meanwhile, Marquinhos and Marcelo are both doubtful with thigh injuries, while Kevin Serna is a possibility as he is nearing a full recovery from a calf strain.
Keno, Marcelo and John Kennedy all scored in the second half against Alianza Lima as they were able to claim a narrow come-from-behind triumph.
Gremio possible starting lineup:
Marchesin; Pedro, Ely, Kannemann, Reinaldo; Dodi, Pepe; Carballo, Cristaldo, Soltedo; Costa
Fluminense possible starting lineup:
Fabio; Guga, Martinelli, Melo, Barbosa; Lima, Alexsander; Arias, Kennedy, Keno; Elias
We say: Gremio 1-1 Fluminense
Throughout the tournament, Fluminense have frequently made strong half-time adjustments, and we believe their resiliency will enable them to claim a result in a place that has proven to be quite difficult for them over the past few years.