Wales fullback Leigh Halfpenny looks set to miss his country's opening matches in the Six Nations.
Scarlets head coach Wayne Pivac revealed Tuesday the fullback has been ruled out for between three and five weeks after seeing a concussion specialist.
Halfpenny has not featured for club or country since he was forced off during Wales' 9-6 victory over Australia during the November international series following a heavy, late challenge from Wallabies centre Samu Kerevi.
Halfpenny was then selected to play for the Scarlets against Cardiff Blues at the end of 2018, but withdrew after suffering headaches.
Now, Pivac has revealed a further medical assessment resulted in the decision to keep Halfpenny, 30, on the sidelines for another extended period.
"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.
"We will pass on the medical information to the Welsh Rugby Union. That will then be [Wales head coach] Warren's [Gatland] call as to what he does, because the tournament runs for longer than that.
"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 come first.
"Lots of players have come back from it [concussion] before. 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."
Wales' opening Six Nations game is against France in Paris on Feb. 1, followed by an appointment with Italy in Rome eight days later.