The 27-year-old was forced to stop after only 10 minutes of Sunday's session, leaving him as a concern for the Selecao's next match
The Zenit St. Petersburg forward featured as the Selecao kicked off the competition with a 3-1 success over Croatia, though he was forced to leave his team-mates prematurely as they continued their build up for the North Americans, who they will meet at Fortaleza’s Stadio Castelao.
After taking part in training for about 10 minutes on Sunday, the forward was forced out with a thigh problem. Nevertheless, he is optimistic of featuring.
"I'm fine, I'm cool," he told the press. "I prefered to exercise caution, as there is only two days before the game.
"I'll travel with the squad but it's Scolari who will decide at the last minute. If I play it's because I can give my best."
Although team doctors have not yet commented on the severity of the problem, there is a chance that the forward could miss the Mexico clash.
His absence would force head coach Luis Felipe Scolari to change the dynamic of the side, with some suggestions that Ramires could be drafted in as an additional body in the midfield, though Bernard, who replaced the 27-year-old midway through the second half of the opening game, and Willian would represent more attack-minded alternatives.
Hulk has won 36 caps in total for his country and has scored nine goals in those fixtures, often playing out on the right wing, which allows him to cut inside and shoot off his stronger left foot.