They are also looking to get overweight former Brazil striker Ronaldo match fit in time for the away match against "Flu" in Rio on Wednesday.
Past the halfway mark in the championship, Flu lead the table with 41 points from 20 matches. Corinthians are second with 38 points and a game in hand.
Ronaldo, whose star has waned outside Brazil to the point the distinction has to be made with Portugal's Cristiano Ronaldo, is coming back into the side at this critical point after almost three months battling injury and weight problems.
The former World Player of the Year scored with a penalty this week in Corinthians' 1-1 draw with Atletico Paranaense, the same team against which he had netted his only other goal in the championship, also from the spot in May.
Coach Adilson Batista is unsure whether to play Ronaldo against Gremio to give him more time on the pitch or leave him to work calmly in training.
"We've got to go easily. It's three months out, he had a game last week, came back and held up well," said Batista, referring an August 29 match against Vitoria.
"He's still got to improve a lot. He wants to and that's the most important thing," Batista told reporters in the early hours of Thursday after the match in Curitiba.
CENTENARY YEAR
Corinthians, seeking the title in their centenary year, want to make the most of Ronaldo's knack of scoring decisive goals - he still holds the record of 15 at World Cups having helped Brazil lift their fifth title in 2002.
Fluminense, who first visit Atletico Goianiense at the weekend, will be looking to avenge a 1-0 defeat away to Corinthians earlier in the season on Wednesday.
However, Flu will not be hosting Corinthians at the Maracana where they have enjoyed the advantage of huge home crowds to spur them to the top of the table.
The giant stadium has been closed for refurbishment for the 2014 World Cup and Flu will play at the Enganhao, home of Rio rivals Botafogo.
"We're in first place, fighting for the title, and it's essential to support our players. To be champions our fans have to be by our side," coach Muricy Ramalho told reporters.
"Against Corinthians, it's down to the fans to take charge of the stadium. We mustn't let (Corinthians) do that. It's our home, the stadium is in Rio de Janeiro."
