Williams, Shingler will also be ready for Six Nations
George North has been given the green light to return to action after recovering from a neck injury.
The Wales wing was stretchered off in the Scarlets' 47-17 defeat to Ulster earlier this month raising fears over his availability for the Six Nations.
But he has returned to full training and is available to start in the Scarlets' clash with Clermont, in which they hope to avoid a European Cup whitewash.
"Everyone was concerned about the bump George took in Ulster but he seems to have responded relatively well," said Scarlets forwards coach Danny Wilson.
"George being George, he has been very diligent and a good professional, so he's recovered quickly."
But the Scarlets will be without Scott Williams, after the Wales centre injured his shoulder against Leinster.
The 2012 Triple Crown hero was on Tuesday selected in Rob Howley's squad for Wales' Six Nations defence.
But both Williams and fellow sidelined international Aaron Shingler are expected to recover in time for the Championship opener against Ireland on February 2.
"We are still recovering from a game where we made a ridiculous amount of tackles," added Wilson.
"Scott is a quality player and will always be missed when he is not available.
"We hope it should be a bump and it provides an opportunity for someone else.
"Shingler took part in full training on Tuesday morning and we are waiting to see if there is any reaction."