World Cup hosts Brazil could have a new injury problem on their hands after Willian withdrew from a training session on Saturday with an apparent back problem.

The Chelsea midfielder, who has been on the fringes of the Brazil World Cup side so far, appeared to hurt himself in a challenge with Hernanes at the team's base in Teresopolis.

Coach Luiz Felipe Scolari may need to call upon Willian for Tuesday's semi-final against Germany in Belo Horizonte, especially with star man Neymar now out of the rest of the tournament because of a fractured vertebrae.

Neymar suffered the painful injury in the second half of Brazil's 2-1 quarter-final win against Colombia in Fortaleza on Friday and will be out of action for as much as six weeks.

In addition, captain Thiago Silva, who scored Brazil's opening goal against Colombia, will miss the Germany encounter due to suspension.

However, influential midfielder Luiz Gustavo will provide a boost as he is available again after serving a one-match suspension.