The Ospreys try machine heads into his final World Cup determined that Wales do themselves justice following a painful pool stage exit in France four years ago.
Fiji, their conquerors on that occasion, return for another crack at destabilising Wales' ambitions in Hamilton early next month, by which time Williams and company will have faced South Africa, Samoa and Namibia.
It all starts on Sunday with a Pool D clash against the Springboks, opponents Wales have beaten just once from 25 previous attempts stretching back 105 years.
Recent form, though, suggests Wales have more than a fighting chance of bucking that trend, having arrived in New Zealand with five victories from their last seven Tests.
They also have the knowledge that on two of the last three previous appointments with South Africa, Wales held comfortable leads before being reeled in.
"We don't dwell on 2007, we dwell on what has happened recently," said Williams, who is set to win his 82nd cap this weekend.
"The last World Cup was very disappointing in the manner we went home. We only had ourselves to blame.
"In a World Cup, you have only one chance, really. If you go out and under-perform like we did last time, you are going home early.
"We certainly don't want that to happen again.
"We've worked very hard pre-World Cup on first of all making sure we are fit and ready for these big physical games.
"But almost more importantly, you have to be mentally tough for these big competitions.
"It is tough, and it does play tricks on your mind playing these games, but the confidence in the camp at the moment is great.
"The attitude in training has been fantastic from the start. There is a nice feeling of self-belief in the camp. Perhaps we've lacked that in the past.
"We will take every game as it comes, and we are preparing at the moment for a very tough South African side."
Wales will have no time to ease themselves into a tournament that sees them facing Samoa just seven days after meeting South Africa, but assistant coach Robin McBryde is unruffled by facing the Springboks on the tournament's opening weekend.
"We look at it in a positive way," he said.
"Obviously, both sides will try to surprise each other, so first-up it is a good thing, that is the way we're approaching it.
"But it will be quite a challenge. They are a big team, very physical, and they are the reigning champions, so they won't want to relinquish their crown that easily.
"Our motivation is to start well."
For their part, South Africa have oozed a quiet confidence all week that they can launch their bid for back-to-back world titles on the right foot.
"You want to have a little bit of flexibility in what you are able to do," said Springboks assistant coach Dick Muir.
"But I think a lot of teams get too caught up in worrying about the opposition, whereas you've got a job to do that presents you with certain opportunities.
"You have got to be able to exploit those opportunities and that is where the flexibility and decision-making comes in.
"If you have a look at our squad overall, we've gone for mature, well-experienced guys that are tried and tested under pressure situations.
"We know the southern hemisphere sides better - we are used to playing against them - so there is more knowledge about what to expect compared to northern hemisphere sides who we tend to only play once a year.
"But we've certainly had a lot of time to be able to evaluate the Welsh and have a look at all their players individually.
"They have really got some good young talent coming through, so it will be interesting."
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