Triple Crown hero Williams aims to make the most of starting spot against Australia.
Triple Crown hero Scott Williams is determined to grab his chance at centre stage on Saturday. (KO 11am UK time)
The Scarlets midfield ace had to contend with a place on the bench during the Six Nations, with Jamie Roberts and Jonathan Davies established as the central axis.
But Williams played a super-sub role and scored the famous match-winning try at Twickenham as Wales clinched the Triple Crown.
Now, with Roberts ruled out with a knee injury, Williams hopes to replicate his Triple Crown form from the outset against Australia.
"I'm just really happy to have the opportunity to start a game," said the 21-year-old. "I've played a lot coming off the bench, with Jamie being in great form.
"This is my opportunity now and I will do my best to try and take it. It's my big chance on the weekend."
Williams, who will win his 13th cap in Brisbane, was selected ahead of James Hook and Ashley Beck. He will form an all-Scarlets midfield with Rhys Priestland at fly-half and Jon Davies at outside centre.
He reckons the familiarity will be a major advantage but insists Wales face a daunting challenge against a wounded
"I think it's an advantage because we've trained and played a lot together," added Williams. "We are used to each other.
"We know we are going to have our work cut out. Australia are not going to be a pushover. They had a really scrappy game against Scotland and were unlucky there.
"But we are just concentrating on what we are taking into the game now. We have got a massive opportunity to put a stamp on a southern hemisphere side."
The WRU has teamed up with Crawshay's to tour Georgia in June. The side, which will be called the Crawshays WRU President's XV, will play Emerging Georgia twice, in a tour which supports the Welsh Government's efforts to grow relations between the two countries.
Wales Sevens are looking to re-group after a disappointing tournament last time out in South Africa. The next double leg in New Zealand and Las Vegas offers Gareth Williams a chance to redeem themselves.
Wales Women's head coach Rhys Edwards was at Llandovery to see the conclusion of an entertaining Women's Regional championship where any one of three teams were in contention for title glory on the last day of action.