Williams, who had been used exclusively in the centres throughout the tournament, started on the wing and acquitted himself with credit in an unfamiliar position.
"I think I've surprised myself, how well I went on the wing, I didn't think I could do it," he told a news conference today.
"Some people didn't think I could play rugby and I showed them that I can. I'm always a confident player so if I'm put out there I know I'll do the job as best I can, just do all the little things and hopefully it comes good."
Williams's immediate priority is to ensure his place in the New Zealand 22 for Sunday's semi-final against Tri-Nations champions and twice World Cup winners Australia.
"Just like the rest of the boys, we all want to be involved. The competition is fierce within the team, but it's a good competition and it brings out the best in us. We all want to be there and we all know the magnitude of the event," he said.
Williams's popularity with the All Blacks' supporters is in direct contrast to the reception accorded Australia's New Zealand-born flyhalf Quade Cooper, who was jeered and booed each time he touched the ball in the Wallabies' quarter-final against South Africa.
"He's a good mate but on the field it's a different story. I want to win and he wants to win," Williams said.
"Obviously us being a proud rugby nation, we see him as the enemy so to speak, but I think he's handled himself pretty well. I think it's kind of a sign of respect as well because if people are hating on him that much, it just shows how good a talent he is."
All Blacks lock Brad Thorn, who has represented Australia at rugby league, described the rivalry between the trans-Tasman neighbours as "cheeky" and "fun".
"I love challenges and these guys have done really well to get where they are, same for us," he said. "We're both going in there, it's going to be an intense game and I'm sure everyone is going to enjoy it."
Scrumhalf Andy Ellis added: "We love getting one over them. We're a smaller country than them, so it makes it even sweeter when we do."