Brazil striker Hulk limped out of training and could be a doubt for Brazil's match against Mexico on Tuesday
The Zenit St Petersburg striker hobbled out of a training match after training.
He received some treatment on the sideline before making his way inside.
Hulk did not return and Brazil manager Luiz Felipe Scolari may be forced to change the lineup that beat Croatia 3-1 in the tournament opener.
The 27-year-old did not last the full 90minutes in the controversial win against Croatia, making way for Bernard after 68minutes.
Hulk did not start the training session at their Granja Comary training complex but limped away with his head bowed.
Scolari drafted Ramires into Hulk's place after he withdrew, giving a possible hint as to what starting XI he may opt for on Tuesday.