Brazil starting striker Hulk left the team's training session with an apparent muscle injury in his left leg on Sunday, two days before his side faces Mexico at the World Cup.

Hulk practiced for less than 15 minutes when he felt something in his leg and left the field.

The forward was walking without a limp, but then sat down on a bench and lowered his head in apparent dismay. A few moments later, he went to the locker room accompanied by one of the team's doctors.

The Brazilian federation was yet to comment on the injury, which apparently happened after he scored a goal during the session.

The injury came in one of the team's final practices before Tuesday's match against the Mexicans in Group A. Brazil travels to the northeastern city of Fortaleza on Sunday afternoon.

Hulk, who plays for Zenit in the Russian league, put his hand on his left leg when doctors arrived to treat him on the bench. He had already felt discomfort in the leg during the opener against Croatia, when he was substituted late in the match.

If Hulk can't play, 21-year-old Shakhtar Donetsk striker Bernard would be his likely substitute in Brazil's attack for the match against Mexico.

Brazil had been injury free since it started its World Cup preparations in late May, but it was a tense training session in Teresopolis, outside Rio de Janeiro.

Bernard stayed on the ground for a few moments after a foul by David Luiz, and the defender was later hurt in a challenge by midfielder Luiz Gustavo. Both players were down briefly but recovered.

Coach Luiz Felipe Scolari ended the training session after the contact between Luiz and Gustavo.