The fact that it was a 13-minute cameo on the wing - a position he had never before played at the top level - is all the more impressive.
With Rhys Webb, Gareth Davies and Mike Phillips for competition, just making the 31-man World Cup squad was a worthy achievement but in less than a quarter of an hour at Twickenham Williams justified his selection.
The 25-year-old's deft chip set up Davies for the try that would draw an injury-hit Wales level in a mammoth Pool A clash, before Ospreys fly-half Dan Biggar booted them to a monumental triumph.
The World Cup, meanwhile, comes off the back of arguably Williams' best ever GUINNESS PRO12 campaign with Cardiff Blues.
With five tries in 11 starts, he was a bright spark in an otherwise disappointing campaign for the Blues and when he returns to club action this season, Williams will no doubt be a massive player once more.
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