The GUINNESS PRO12 rivals go head-to-head, with Scarlets seaking their first win in this year's competition, while their Welsh rivals will be looking to build on their slender victory over Newcastle Falcons last time out.
Opportunities for Williams have been limited so far this season but with coach Wayne Pivac expected to ring the changes, the 21-year-old intends to gobble up his chance to impress.
"There's no extra pressure on me to perform. I'll always put my hand up for selection, regardless of the situation or circumstances," he said.
"There are quite a few news boys that have come in, so I see myself as one of the leaders in the backs this week, and intend to use my experience.
"It's difficult to know what we can expect from Cardiff, because there will be a few boys rested. They had a good win against Newcastle and I'm sure they will expect more of the same.
"We need to stick to our own game and put into practice what we have been working on week-by-week, developing more of a pattern to our play."
Should Williams impress, he will hope to gain further opportunities to displace Fijian international Michael Tagicakibau in the No.11 shirt.
A run in the team could see him build on the experience of being part of the Wales squad that toured South Africa in the summer but for now, Williams is determined to focus on his club rugby.
"I do want to play week in, week out, but it's been tough this year," he added. "Hopefully the opportunity for a run of games will arise soon.
"When a new player comes in you just have to bite your lip and get on with it. It's up to me to impress in training and when the chance comes on the pitch if I'm going to get my place back.
"Going to South Africa in the summer was great and something I'd love to do more regularly. But first I have to be playing week in, week out for Scarlets."
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