A week after pushing South Africa to the brink of defeat, Wales dug deep for a pricless 17-10 Pool D victory over Samoa that kept them in World Cup contention and set up a possible quarter-final clash against Ireland.
Williams' 55th touchdown in Wales colours not only clinched the win, but moved him ahead of Ieuan Evans and Gareth Thomas as his country's record World Cup try-scorer with eight in eight games.
More importantly, though, it enabled Wales to maintain a route towards the knockout phase accompanied by a simple equation - wins against Namibia, Fiji and probably Ireland equals a semi-final place for the first time since 1987.
"You saw a different side to our game," said Ospreys wing Williams, reflecting on the Samoa success.
"We didn't want to play too much rugby because their defence was very strong. I am just glad we have got a different side to our game.
"We were determined to continue on from playing well (against South Africa) last week against Samoa, but we made too many mistakes and handling errors, losing the ball.
"But we still won. That's the key thing. The mental and physical strength of this Wales squad is better than any I have been involved with previously.
"It was very frustrating at times against Samoa, but we won the game. Perhaps that is the sign of a good team."
Williams once again turned up in the right place at the right time to sniff out a try that gave Wales a scent of victory.
And it underlined how vital a player he remains to Wales coach Warren Gatland, even though the 34-year-old has indicated several times that this season will mark his Test rugby retirement.
"Time does catch up with you," he added. "As somebody pointed out to me, I am the oldest on tour.
"At the moment, I'm still keeping up with the youngsters and enjoying it, although (team-mate) George North is making me feel old."
Asked if he would be available for Wales' post-World Cup Millennium Stadium appointment with Australia on December 3, Williams said: "Let me see how the World Cup goes.
"I will see how my knees are and how my body is going.
"There are no easy game in World Cups these days. Prior to this World Cup, nobody had seen Romania and Georgia competing so well.
"And Canada played so well against France yesterday. For a while, it could have gone either way.
"The lesser sides have put their hands up and keep developing. They are certainly catching up on the world stage.
"Games are just as physical, regardless of who you are playing. They are all out there to win against the bigger sides in the World Cup, so it's great."
Wales will now hope that injured pair James Hook and Dan Lydiate can make quick recoveries from injuries that forced them off against Samoa.
And Williams reflected on the punishing physical nature of the Samoa contest today as the Wales squad prepared for some time off before returning to training on Wednesday.
"I don't really know what the outcome is with James at the moment, but we are in a competition and no-one wants to be injured," he added.
"I hope James is back sooner rather than later because he's a massive asset. I hope his injury isn't as bad as it looked.
"I didn't see how James got his injury - I was still looking for my rib on the 22! These type of games are physical and they take it out of you. You do get bumps and bruises.
"What you have got to do against Samoa is match them in all aspects, and we had the likes of Jamie Roberts and George North running hard and straight."
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