His overall game has improved significantly since his Achilles injury suffered at the Olympics last year, helped by his relentless training regime and obsession for improvement. He can use his 1.94m frame to brutal effect on defence, but it is his attack, and particularly his offloading ability, which truly sets him apart.
Marking him will be Ben Te'o, a Kiwi-born former league player just like Williams. But the All Blacks' No12 has a unique skillset which could prove to be a point of difference for Steve Hansen's men.
Conrad Smith still hasn't forgiven Hansen for replacing him with Williams at halftime of the World Cup final against Australia at Twickenham two years ago, but it was quickly apparent that the All Blacks coach had made the right decision. Williams made two offloads in the space of seconds once play re-started, the second of which resulted in Ma'a Nonu's crucial try from 50m out.
With Rieko Ioane, Ryan Crotty, Israel Dagg and Ben Smith ready to take advantage of similar opportunities, the Lions will have to be on high alert for the entire time Williams is on the field.
After the Blues victory at Eden Park in the Lions' second tour match, coach Warren Gatland believed his side coped fairly well with the opposition's offloading game. "It was a moment of magic which you do get from New Zealand teams," he said.
The trouble is, these All Blacks only need a couple of magic moments and the game could quickly be beyond the Lions.
Te'o, the man from Orewa, north of Auckland, who left for the bright lights of the NRL as a 17-year-old, and now represents England, spoke with confidence about his task in attempting containing Williams in his first test for the Lions.
"I've been lucky enough to play against him a couple of times," Te'o said. "Obviously we're both at 12 but whether we meet on the field ... who knows what's going to happen. I'm wary of his abilities, I know what he can do in big games, I've seen it before, so we'll be preparing well for it.
"He's a great player, so we'll have to see what happens on Saturday."
Williams' natural ability and his training regime, and even his fasting, will have him primed to deliver, and even if he doesn't manage to stretch his long arms and get a pass away, the threat he poses should create space outside him. Like flies to an old meat pie was Hansen's analogy.
For Williams, who was overjoyed at the Blues' victory over the tourists for what it meant to the team's younger members as much as himself, the whole occasion will be taken for what it should be - enjoyment and the chance to put his God-given talents to use.
He told the Daily Telegraph recently: "Every athlete has to make sacrifices and I believe fasting can only enhance me as a sportsman, it gives me mental discipline.
"It helps with my mental strength, and sport is all about mental strength."
