Brazil coach Luiz Felipe Scolari declared Sunday's training was "all wrong", indicating his starting line-up is far from confirmed.
Scolari split his 23-man squad into two teams a number of times over the weekend for practice games as the 65-year-old coach experimented with different potential starting XIs.
But after Sunday's training session in Teresopolis, Scolari indicated he may have to rethink his preferred starting side ahead of the World Cup, with a friendly against Panama coming up on Tuesday.
"I did not like the training, I did not like anything, all wrong," Scolari told Globo TV.
"When I do not like something I have to find a solution, put it on the field, until I'm satisfied."
Paulinho, Fernandinho and Thiago Silva will all likely miss the clash with Panama on Tuesday due to minor injuries, with Scolari particularly eager to rest the Paris Saint-Germain star.
"Thiago is recuperating...we have two friendly games before the World Cup and it is preferable that he gets better," Scolari told Fox Sports.
Hernanes played alongside Luis Gustavo in Sunday's practice game and could start in midfield versus Panama.
Oscar and Daniel Alves could also be benched after they were swapped into the second XI on Sunday for Ramires and Maicon.