The Welshman averaged 94.36 and hit three 100-plus finishes as he won for the loss of just four legs.
It came after Williams had scraped through his first match, surviving match darts against Gary Stone, and this was much more like it.
Williams, seeded two this week, checked out from 101, 121 and 122 as he went through the gears, powering to a whitewash win which sets him up perfectly for the quarter-finals.
In the evening session, Paul Hogan defeated Martijn Kleermaker 4-1. Hogan averaged just shy of 100 in his outstanding victory, hitting six 180's on his way to booking his place in the quarter-finals for the first time since 2016.
At the age of 56, 'Crocodile Dundee' is arguably playing the best darts of his career and its the second time this week he's averaged as highly, earning rave reviews in the process.
Mario Vandenbogaerde was on top form, averaging 90.63 to cruise to a 4-1 victory over Dennie Olde Kalter.
The Belgian overcame a minor blip towards the end of the match to set up a quarter-final clash with David Evans.
In the women's draw, Corrine Hammond took a step closer to what would be her second final with a 2-0 victory over Laura Turner.
Her reward will be a meeting with either top seed Lisa Ashton, who averaged 79.90 en route to a 2-0 victory over Lorraine Winstanley in the evening session.
In the final match of the afternoon, teenager Beau Greaves beat third seed Aileen de Graaf 2-1.
On her 16th birthday, Greaves produced a stunning display in a high-quality match, averaging 86.11 on the way to booking the first of what will surely be many semi-final appearances.
Greaves quickly took control of the match when winning every leg in a one-sided opening set before doubling her lead with more fine throwing.
She looked sure to close out the match when taking charge in set three but de Graaf kept her hopes alive with a wonderful checkout of 126 to steal the set.
However, Greaves wasn't perturbed and was soon back in the ascendancy, dominating the fourth set to close out the match.
Greaves will meet Mikuru Suzuki in the semis, who followed up her memorable appearance at the PDC World Darts Championship last month with a 2-0 victory over Anastasia Dobromyslova in the evening session.
The Japanese player clinched victory with a match-winning double, averaging 77.56, and setting up the meeting with Greaves.
Thursday results & Friday schedule
Thursday January 9
Afternoon Session (1pm)
Men's Third Round (Best of 7 sets)
Women's Quarter-Finals (Best of 3 sets)
TV Coverage: Quest (freeview channel 37) & Eurosport
- Corrine Hammond 2-0 Laura Turner
- (2) Jim Williams 4-0 Ryan Hogarth (15)
- Aileen de Graaf (3) 1-2 Beau Greaves (6)
Evening Session (7pm)
Men's Second Round (Best of 7 sets)
Women's Quarter-Finals (Best of 3 sets)
TV Coverage: Eurosport
- (1) Lisa Ashton 2-0 Lorraine Winstanley (8)
- (2) Mikuru Suzuki 2-0 Anastasia Dobromyslova (7)
- Dennie Olde Kalter 1-4 Mario Vandenbogaerde (11)
- (7) Martijn Kleermaker 1-4 Paul Hogan
Friday January 12
Afternoon Session (1pm)
Men's Quarter-Finals (Best of 9 sets)
Women's Semi-Finals (Best of 3 sets)
TV Coverage: Quest (freeview channel 37) & Eurosport
- Wayne Warren v Chris Landman
- Lisa Ashton v Corrine Hammond
- David Evans v Mario Vandenbogaerde
Evening Session (7pm)
TV Coverage: Eurosport
- Paul Hogan v Jim Williams
- Beau Graves v Mikuru Suzuki
- Scott Waites v Scott Mitchell
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