Williams underwent groin surgery last month and has not played since returning home from the Lions' tour of New Zealand.
A comeback appears imminent though, which will be music to Wales coach Mike Ruddock's ears, given that he has already lost injured Lions Gavin Henson and Gethin Jenkins from his autumn plans.
Williams was planning to take part in contact training with the Ospreys ahead of Friday night's Celtic League clash against Connacht, while he believes opening European Cup appointments with Stade Francais and Clermont Auvergne later this month are realistic targets.
Wales launch their autumn programme against New Zealand on November 5, then face Fiji, South Africa and Australia.
"I am pretty much back to 100%, and hopefully, I can play as soon as possible," said Williams.
"I should be back for the opening European Cup games, maybe sooner. I haven't taken any contact yet, so I will probably do a bit of that with the Ospreys and see how training goes.
"Touch wood, everything will go well and I will be back as soon as possible.
"The injury was something that has developed over time, but I only started to feel it towards the end of the Lions tour. With it having been such a long season, it just took its toll at the end.
"And I had to have it fixed before the new season started. The intensity of rugby at the moment is a lot higher, the games have got a lot more physical as well, and they are a lot quicker. You have got to be on top of your fitness to compete, really.
"It was a massive season as far as most of the Welsh boys were concerned, with the Grand Slam win, the Ospreys winning the Celtic League and being picked for the Lions tour, and it did take its toll."
Wales, meanwhile, will break new ground on November 26 when they tackle the Wallabies.
The reigning Six Nations champions will wear a new black jersey, launched by their kit supplier Reebok, to commemorate the Welsh Rugby Union's 125th anniversary.
It will be the first time Wales have not worn red jerseys in a Test match against one of their fellow International Rugby Board foundation unions - Australia, South Africa, New Zealand, England, Ireland, Scotland or France.