The 26-year-old has been on the sidelines since he suffered groin and hip injuries during Wales' autumn international against Georgia and there had been fears he could be the latest Dragons star to be ruled out of the Six Nations.
However, Saracens director of rugby Mark McCall is confident Williams will be in his matchday squad for this weekend's crunch European Champions Cup clash against Ospreys.
"If there are no ill-effects from today's training session, which was the tougher of the two days, then he's got a great chance of being involved in the squad," said McCall, whose Sarries side must beat the Welsh region to keep alive their hopes of progressing to the quarter-finals of the Champions Cup.
"We've taken our time but he looks pretty good, he just needs to make sure there's not a reaction.
"It's always a calculated gamble to bring someone back who hasn't played for a bit.
"But I think you do have the odd exceptional player who is able to do that and is good enough for you to want to put that player in. Liam is probably in that category."
Williams' return to action will be a weight off Wales coach Warren Gatland's mind as he gets set to name his Six Nations squad on January 16 having already lost Sam Warburton, Dan Lydiate and Jonathan Davies to injury.
Gatland also has concerns over the fitness of Taulupe Faletau, George North, Ross Moriarty and Hallam Amos, who all face a race against time to play some part in this year's tournament.