The forward was forced to stop after only 10 minutes of Sunday's session, leaving him questionable for the Selecao's match against Mexico.
The Zenit St. Petersburg forward featured as the Selecao kicked off the competition with a 3-1 win over Croatia, though he was forced to leave his teammates prematurely as they continued their build up for El Tri, who they will meet at Fortaleza’s Stadio Castelao.
After taking part in training for about 10 minutes Sunday, the forward was forced out with a thigh problem. 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.
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His absence would force 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. 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 and scored nine goals for Brazil, often playing out on the right wing, which allows him to cut inside and shoot off his stronger left foot.