Leigh Halfpenny looks set to miss the start of Wales' Guinness Six Nations campaign.
The Scarlets full-back has not played since suffering concussion during Wales' victory over Australia on November 10.
Halfpenny has seen a specialist, and Scarlets head coach Wayne Pivac reported on Tuesday that the player would not feature for "three to five weeks".
Wales' opening Six Nations game is against France in Paris in February 1, followed by an appointment with Italy in Rome eight days later.
Halfpenny, 30, went off late in the Australia match after being on the receiving end of a late challenge from Wallabies centre Samu Kerevi, who avoided any punishment.
"Leigh has seen the specialist and won't be used for the next three to five weeks," Pivac said.
"He will continue training and doing what he's been doing, and then he will be reassessed.
"It will be somewhere between three to five weeks, but these things take time. That's the time-frame we're looking at.
"He's running, he's training, and from time to time I think he's been having bouts of (headaches).
"He's as frustrated as anybody is, but his health and well-being comes first.
"Justin Tipuric and Aaron Shingler have had spells out, and both those players have returned to the top of their game at some point.
"There's no reason why that won't happen with Leigh."