Renato Gaucho's men have lost three league encounters on the trot, leaving them third-bottom and four points adrift of their opponents who could slide into the relegation spots this weekend.
Match preview
Last season's runners-up are in free fall this year, underlined by another loss for Clube de Todos at Sao Paulo on Thursday.
The defeat was the 10th suffered by Gaucho's side in 15 top-flight matches, two shy of their total losses in their title-challenging 2023 campaign.
Defeating Operario in the domestic cup has not proved to be the turnaround that supporters desired, with the midweek defeat the club's third on the trot heading into round 18's fixture.
While they have played two games fewer than most sides in the league, Imortal Tricolor aim to notch their first top-flight success since cellar-dwelling Fluminense in late July, a result that was sandwiched between draws against Atletico Goianiense (1-1) and Palmeiras (2-2).
Seeking their first home triumph in nearly a month, Gaucho hopes his side can exploit another struggling side on Sunday.
Vitoria, for their part, may be four points clear of last season's runners-up, but they will back themselves to take advantage of a club that has been defeated in four of their recent six Brasileiro games.
Thiago Carpini will be aware of his side's struggles on their return to the big time after six years allied with Gremio's second-place finish last season, but neither team is playing at their best before gameweek 18, making it anyone's game.
Leao da Barra's 3-1 loss at Fortaleza in the midweek round was their fourth loss in five league fixtures and 10 overall, a joint-high in the top division.
The ongoing run is reminiscent of their start to the season in which only one point was picked from an available 18 before seemingly finding some form over an undefeated four-game sequence (two wins).
However, that turnaround was short-lived as Imortal Tricolor's results have dipped in recent gameweeks, leaving them looking over their shoulder.
Carpini's men could drop into the bottom four places this weekend if Corinthians (both clubs are level on points) better their round 18 result.
Gremio Brasileiro form:
D
W
D
L
L
L
Gremio form (all competitions):
W
D
L
L
W
L
Vitoria Brasileiro form:
W
L
L
W
L
L
Team News
Edenilson and Franco Cristaldo are doubtful with muscle injuries, while Gustavo Martins' participation is uncertain.
Expected to miss out for Gremio are former Chelsea striker Diego Costa (muscle), Andre (ankle), Jhonata Robert and Mila (both have knee injuries).
Luan Santos was withdrawn after 21 minutes against Fortaleza, making the Vitoria midfield man's participation unlikely on Sunday.
Dudu and Rodrigo Andrade are reportedly absent for disciplinary reasons while Caio Vinicius (thigh) and Camutanga (knee) are out injured.
Gremio possible starting lineup:
Marchesín; Pedro, Ely, Nata, Reinaldo; Villasanti, Pepe, Dodi; Pavon, Galdino, Soteldo
Vitoria possible starting lineup:
Arcanjo; Lepo, Uvini, Leonardo, Esteves; Naldi; Everaldo, Mota, Oliveira, Janderson; Alerrandro
We say: Gremio 2-1 Vitoria
Vitoria have claimed only one road victory in eight attempts, losing five on their travels, and that sole triumph came against the league's bottom club.