The hosts fended off the challenge of lower league side America RN in the last round, while their visitors saw off Operario at the second time of asking.
Match preview
Corinthians claimed a 2-1 win over America RN on May 23 to secure an overall 4-2 aggregate triumph and book their place in the last 16 of this year's Copa do Brasil.
That was the second of three straight wins for Ramon Diaz's men, but they have flattered to deceive ever since, winning just three of the subsequent 14 matches across all competitions.
O Timao suffered late heartbreak in their most recent league outing - a 2-1 defeat against Atletico Mineiro on Sunday which left them 15th in the Brasileiro table just past the midway point of the season.
While Corinthians have endured a torrid time in the league, they will be looking to enjoy another deep cup run off the back of a semi-final appearance last time out which ended in defeat to Sao Paulo.
Wednesday's hosts welcome their visitors unbeaten in nine straight meetings between the teams, although it is worth noting that seven of the games have ended all-square.
Gremio were held to a 0-0 draw in the opening leg of their Copa do Brasil tie against lower league side Operario before going on to claim a routine 3-1 victory in the second leg on July 14.
That snapped a run of three matches without a win for Renato Portaluppi's men, who have since picked up seven points from four matches to sit 16th in the top tier of Brazilian football.
Despite managing just one goal in their last outing, where they narrowly beat Vasco da Gama, O Clube de Todos recorded a season-high 22 shots and could have easily claimed a bigger win on another day.
Nonetheless, Thursday's visitors have cause for concern heading into yet another game on the road having failed to win any of their last seven away matches since early June.
Corinthians Copa do Brasil form:
Corinthians form (all competitions):
L
L
W
W
D
L
Gremio Copa do Brasil form:
Gremio form (all competitions):
L
W
L
W
D
W
Team News
Brazilian duo Ruan Oliveira and Maycon are both unavailable for Corinthians as they remain sidelined with long-term injuries.
Twenty-five-year-old Diego Palacios also misses out due to a knee problem he suffered earlier in the campaign.
Yuri Alberto has scored in both of his last two appearances for the home side and will be keen to come up trumps once again.
Yeferson Soteldo has been directly involved in three of Gremio's last five goals, making the Venezuelan one to keep an eye on.
Diego Costa remains without an appearance since June, and the 35-year-old is still a considerable way off making his return to action.
Brazilian trio Andre Henrique, Jhonata Robert and Lucas Mila are all out of contention for the away side through respective injury problems.
Corinthians possible starting lineup:
Souza; Hugo, Torres, Ramalho, Fagner; Garro, Ryan, Santana, Raniele; Alberto, Romero
Gremio possible starting lineup:
Marchesin; Ely, Kannemann, Jemerson; Pedro, Villasanti, Dodi, Reinaldo; Pavon, Cristaldo, Soteldo
We say: Corinthians 2-1 Gremio
Goals have been a constant feature of this fixture over the years, and we expect Thursday's affair to be no different.