Brazil want midfielder Kaka to play in next month's Olympic qualifying tournament in Chile, a move that is likely to spark a tug-of-war with his Italian club AC Milan.
Under-23 coach Ricardo Gomes named 17 players for the tournament on Monday but left three places open in the hope he can select Kaka, one of Serie A's revelations this season, Sevilla's Julio Baptista and another European-based player.
"Kaka and (fellow midfielder) Julio Baptista have not been ruled out, the situation is not final," he said. "I don't have much patience but these players are worth waiting for."
Brazilian Football Confederation (CBF) national team supervisor Americo Faria said he was still negotiating with the two European clubs, who he said did want to release the players.
Faria also criticised the difficulties he said European clubs created.
"Until we establish the rules of the game any negotiation is going to be very difficult because we are dealing with various clubs in different countries," he said.
"The problems will only be reduced when we have a statute which is obeyed."
Faria added that a tough year of negotiations lay ahead.
"We have to take into consideration that in 2004 we have the Olympic qualifiers, seven World Cup qualifiers, the Olympics themselves and the Copa America.
"Obviously, if any player is selected for all these competitions, he will be with the national team for three or four months and that is a strong argument for the clubs.
"So we're going to try and negotiate."
Brazil, five times winners of the World Cup, have never won an Olympic gold medal in soccer.
Monday's squad included four European-based players, who the CBF said have been released by their clubs.
Squad:
Goalkeepers - Gomes (Cruzeiro), Juninho (Vitoria)
Defenders - Luisao (Benfica, Portugal), Adriano (Gremio), Edu Dracena (Cruzeiro), Alex (Santos), Maicon (Cruzeiro), Maxwell (Ajax, Netherlands)
Midfielders - Paulo Almeida (Santos), Diego (Santos), Elano (Santos), Wendell (Cruzeiro), Fabio Rochemback (Sporting Lisbon, Portugal), Paulinho (Atletico Mineiro)
Forwards - Marcel (Coritiba), Nene (Mallorca, Spain), Robinho (Santos).
