Brazilian football chief Jose Maria Marin has called on his country to go all out to win their first Olympic football title and not use the 2012 Games as a "laboratory" to experiment for the 2014 World Cup.
Brazil will host the football showpiece in two years time and Brazilian Football Confederation (CBF) president Marin, said: "That is my worry.
"A team on the pitch cannot be used a laboratory, we have to show our best. Every time a Brazilian team goes onto the pitch, whether it be masculine of feminine, they have to give everything."
Brazil, the record five-time men's World Cup winners, have finished runners-up twice at the Olympics, in 1984 and 1988. Their women's team were Olympic runners-up in 2004 and 2008.
Brazil coach Mano Menezes will name a list of 18 players on May 11 for the London Games.
And while Marin insisted he did not want to interfere with Menezes's choices, he asked that he be allowed to see the list before it was unveiled.
"(Mano Menezes) deserves all our respect and confidence (but) in every Brazil team what the coaches need to guarantee are the results," said Marin, who gave his backing to Menezes.
"Every time a decision is taken, he (Menezes) will be the first informed, there will never be something in the media.
"I hope that (his resignation) will not happen and I expect that he will lead us to great victories, not only in 2014 but also at the Olympics to start."
Menezes revealed a provisional squad of 52 players last month for the July 27 to August 12 Games including stars Neymar and Ronaldinho.
The coach must call up players of 23 years maximum and has also the right to call up three others without age restrictions.