Williams has played just once in the GUINNESS PRO12 this season - in Scarlets' 30-17 loss to Connacht in January - having previously aggravated an ankle injury during the World Cup before returning to action with Wales.
And now head coach Wayne Pivac has revealed he could be out of action for the rest of the campaign.
"Four to six weeks is what we're told - don't expect to see him in the next few weeks," he said.
"We've had 60 minutes from him so far this season which is disappointing but there's no one more disappointed than Liam.
"We just have to get him right for the latter part and who knows there may be more rugby to come."
Scarlets also confirmed hooker Kirby Myhill will be joining Welsh rivals Cardiff Blues at the end of the season.
The 24-year-old skippered Wales under-20s to third place at the 2012 Junior World Cup, and has notched up 71 appearances for Scarlets, although many of them have come off the bench.
To buy tickets for the GUINNESS PRO12 Grand Final click here. Also follow us on Facebook, join the conversation on Twitter, sign up to our YouTube channel for extensive match highlights and sign up for our newsletter for regular updates on the GUINNESS PRO12.
63x46.png){kind=logo}