Olivier Brouzet looks set to miss France's opening World Cup match against Canada in Beziers on Saturday. The 6ft 8ins lock damaged muscles at the bottom of his spine in training on Monday.
Other injury worries, Thomas Castaignede and Christophe Dominici, both came through yesterday's training session without problems.
But reserve hooker Marc Del Maso is still struggling with a knee ligament injury and is also likely to miss France's opener.