Brazil head coach Luiz Felipe Scolari warned his players against avoiding hard work with their clubs to remain fit for the World Cup.
In the lead-up to Wednesday's friendly against South Africa, Scolari said he would only pick players for the World Cup finals that have good club form.
Brazil will aim to win their first World Cup on home soil when they kick off the tournament against Croatia on June 12.
"They are only called up if they do well at their clubs," Scolari said on Tuesday.
"If not, I will not select them."
The former Chelsea and Palmeiras head coach added: "I've been a club coach and say that players have to die for their teams.
"Clubs are paying salaries."
Scolari will use his team's friendly against South Africa to prepare for Cameroon at the World Cup.
Group A of this year's World Cup finals will see Brazil take on Croatia, Mexico and Cameroon, and Scolari has scheduled friendlies against Serbia, Panama and South Africa before the tournament to test his team against similar opposition.
First up will be their clash with South Africa at Soccer City in Johannesburg and, while Scolari has former Bafana Bafana head coach Carlos Alberto Parreira assisting him, the 65-year-old is looking forward to seeing African opposition up close and learning for himself.
"Yes, the idea when we were invited to play here in Africa was to observe the similarity of African football and to use it when we play against Cameroon," Scolari said.
"We have this match and one more against Serbia and other one against Panama.
"But this was the match we wanted to use to make an observation of African football."
Scolari also confirmed Bayern Munich right-back Rafinha and Manchester City defensive midfielder Fernandinho will start against South Africa.
It will only Rafinha's second cap for Brazil, while Fernandinho will make his sixth appearance.