Brazil's two biggest stars, Marta and Formiga, are struggling with injuries ahead of their women's World Cup last-16 match against France on Sunday, coach Vadao said.
Marta, who became the all-time World Cup record goalscorer with the penalty that gave Brazil a 1-0 victory over Italy and a place in the second round, is not at "100 percent" for the game in Le Havre.
The 41-year-old Formiga has ankle problems and is a doubt for the match.
"We're going to see how she's doing in training this afternoon and maybe we can count on her tomorrow night," Vadao told a press conference on Saturday.
Formiga, who had just picked up her second yellow card of the tournament, came off at half-time in Brazil's second group game with her team leading Australia 2-1 in a match they then lost. She was suspended for the victory over Italy.
Marta started the World Cup with muscular problems. She missed the opening victory over Jamaica and came off at half-time against Australia and before the final whistle against Italy.
Her two goals have taken her to 17 in World Cups, a record for both women and men.
Vadao said he doesn't know if the striker will be able to "play the whole match" against France.
Brazil have never beaten France in a women's international. In eight games they have drawn five and lost three.
"They may be the favourites, but on the field, everything is open," said Vadao, who praised the French players.
"They have a very good aerial game, defend very well and make good use of set-pieces," he added.
Debinha, who, with Marta below her best, has been Brazil's most dangerous creative player, said her team can cope with France's home advantage.
"It's clear they'll have all the fans behind them, but for us it's not important, we're going to play our best football," she said.