Having been placed on standby for a number of previous squads named by Graham Arnold, the off-contract Rotherham winger wasn’t sure when - or if - his time would come.
Delight at finally making the cut - along with elder brother Rhys - for the clash in Busan led to the quick cancellation of his family’s travel plans.
And the determination to make sure he isn’t just a one-time wonder.
“I’ve re-arranged things but I’d pay handsome sums of money to do it again because this call-up means a lot to me,” Williams told The World Game.
“My mum, who used to live near Busan, is coming and it’s just exciting for the whole family.
“If I get the chance to play I’ll be looking to make an impact.
“First and foremost it will be good for the coaches to see what I’m like in training and hopefully I can make sure I’m a part of their choices for the future.”
Having brother Rhys, 30, in the same squad brings added poignancy, as well as stoking memories of 2011 when Ryan made his professional debut against Rhys’s Middlesbrough.
“He was there, playing against me for my Championship debut, and hopefully this time we can be playing on the same side for my Socceroos debut. That would be nice,” he added.
“It would be a bit of a milestone but we’ve got to get picked first.”
The pair join a select band of Socceroos siblings who have featured in squads simultaneously.
The list includes Aurelio and Tony Vidmar, John and Ross Aloisi, the Griffiths clan - Joel, Ryan and Adam, and the McGowan brothers, Ryan and Dylan.
After 39 appearances for relegated Rotherham United last season, Williams is set to bounce back to the Championship with a switch to a new club.
“There has been an offer but there’s no huge rush,” he said.
“I want to go away with Australia first and hopefully make a bit of an impression and re-assess things when I return.”
Williams sees remaining at Championship level crucial to his hopes of maintaining a presence with the national team, with Arnold bringing in six new faces to replace some rested regulars for the Korea camp.
“It’s nice to get a bit of recognition but I need to build on that,” he added.
“Up to now maybe I just haven’t done enough in terms of scoring goals (with just one in the league last season).
“With a team like Rotherham that’s struggling, it’s hard. We were the bookies’ favourites to go down and were fighting an uphill battle.
“Most games we were defending 70 percent of the time. But that’s not the only reason and maybe I could have done better.”