The triple British & Irish Lions tourist has been at the top of the national game since 1996 and the veteran flanker has little doubt that Welsh rugby is in its most-promising state for some time.
Warren Gatland's men provided 12 players to Ian McGeechan's Lions squad that toured South Africa, with 10 of those featuring in the three-match Test series against the Springboks.
However, the 34-year-old knows that strength-in-depth will mean very little to the country's passionate supporters unless the national side can consistently produce winning performances against the world's top teams.
Wales secured a comfortable victory over Argentina last weekend but defeat to New Zealand and a below-par performance against Samoa means there is plenty riding on Saturday's clash with Australia in their final Test match of the year.
"Our strength in depth is the strongest it has been for a number of years, but we've got to back that up with a performance against Australia," said Williams.
"If we don't win next Saturday, it is going to be a disappointing autumn, there is no doubt about that. It's a big game for both teams."
Williams believes the 74,500 fans fortunate enough to have a ticket for the Cardiff showdown will be watching what should be an exciting, free-flowing game between two sides with similarly positive outlooks.
Wales have themselves earned a reputation for producing an exciting brand of rugby and, while the Wallabies may have been on the wrong end of a one-point defeat to Scotland last time out, Williams doesn't expect his opponents to change their own attacking style ahead of Saturday's encounter.
"Wales and Australia play similar styles - we both try to play expansively," added Williams.
"They are normally good games too, with a high ball-in-play time and a lot of attacking rugby. And recently, we've always seemed to play them last up after we have been together for a month during the autumn and started hitting our straps.
"Australia are so innovative as a side. They are a great team to watch, and they can run at you from anywhere. You cannot switch off. I don't think it is a game that is going to be won on penalty kicks."