While the Argentine giants begin this fixture bottom of Group D, Fluminense are five points ahead in first place and on the brink of qualification for the next phase.
Match preview
River Plate head into the penultimate fixture of the Copa Libertadores in mourning after a supporter died when falling from one of the stands at Estadio Mas Monumental at the weekend.
The incident led to the immediate suspension and abandonment of their game with Defensa y Justicia, but the upcoming continental fixture at the same ground is expected to go ahead as planned.
Martin Demichelis's team head into the contest on a three-match undefeated streak, one of those games being in this competition as they salvaged a 1-1 draw at Sporting Cristal.
Although the share of the spoils stopped River Plate from being cut adrift at the bottom of Group D, the club have been left scrapping for a spot in the knockout stages courtesy of their 5-1 defeat at Fluminense on May 2.
Three goals during the final 15 minutes ensured that the scoreline was emphatic, and it means that Fluminense will effectively be assured of a last-16 place if they avoid defeat in the reverse fixture.
If River Plate can prevail, however, they will be within two points of the frontrunners with a game remaining, and potentially in the top two depending on the result between The Strongest and Sporting Cristal.
At a time when River Plate are four points clear in the Argentine top flight with a fixture in hand, Fluminense are only in fifth in Brazil's equivalent.
In all competitions, they had lost four times in succession before they recorded a much-needed 2-1 triumph over RB Bragantino on Sunday.
However, Fernando Diniz will recognise that he requires more from his side at a time when complacency in this competition could prove to be as big of a factor than the recent contrasting form of the two teams since their first meeting.
River Plate Copa Libertadores form:
L
W
L
D
River Plate form (all competitions):
L
W
L
W
D
D
Fluminense Copa Libertadores form:
W
W
W
L
Fluminense form (all competitions):
W
L
L
L
L
W
Team News
River Plate will be without Salomon Rondon after the forward was sent off for his part in a mass brawl versus Sporting Cristal while remaining as an unused substitute.
Captain Enzo Perez is also unavailable due to suspension and injury, with Jose Paradela most likely to deputise in the middle of the pitch if Nicolas de la Cruz reverts back to the right.
With Enzo Diaz still out injured, Andres Herrera should feature at right-back which would see Milton Casco switching to the opposite flank.
Diniz rang the changes at the weekend and achieved the desired effect, with the Fluminense players who started that fixture likely expecting to retain their spots.
Barring any injury issues, that should prove to be the case, although Lele is an option down the middle of the attack with German Cano failing to score on his last six starts.
River Plate possible starting lineup:
Armani; Herrera, Rojas, P.Diaz, Casco; Aliendro, Paradela; De La Cruz, Fernandez, Barco; Beltran
Fluminense possible starting lineup:
Fabio; Xavier, Melo, Nino, Guga; Andre, Martinelli; Arias, Ganso, Lima; Lele
We say: River Plate 2-1 Fluminense
The manner of the defeat in the reverse fixture naturally left River Plate stunned and in a position where qualification is no longer deemed to be a foregone conclusion. However, they are a different side at home, and we feel that their battling qualities will lead to a potentially-decisive victory over the group leaders.