Ireland fly-half Jonathan Sexton is a fitness doubt for his country's Six Nations opener against Italy on 7 February according to French reports.
Newspaper L'Equipe said on Thursday that the Racing Metro fly-half had been banned from playing until 14 February by French Rugby's medical commission.
Sexton has yet to recover from a bang to the head he suffered in Ireland's win over Australia last month.
"He will not play a match until he's 100%," said Racing coach Laurent Labit.
Sexton has not played since Ireland's Australia game on 22 November and has again been left out of the Racing squad for Saturday's Top 14 game against La Rochelle.
The Irish Rugby Football Union's medical staff are expected to assess Sexton's fitness either later this month or early in the New Year.
Ireland's second Six Nations match will see them taking on France at Dublin's Aviva Stadium on 14 February.
If the reports are accurate, Sexton would be available for Ireland's France game but would be in danger of being ruled out of the Rome contest a week earlier.
Sexton's exceptional performances during Ireland's impressive autumn series emphasised his importance to coach Joe Schmidt's plans ahead of next year's World Cup.
The fly-half is in his second year with the French club but will rejoin Leinster at the end of this season.
Sexton will be replaced at Racing Metro by New Zealand star Dan Carter who will join the club on a three-year contract and become the sport's highest-paid player.