Coach Pim Verbeek announced that Williams, Shane Lowry, Tommy Oar, James Holland and goalkeeper Eugene Galekovic missed out on the final squad. Verbeek blamed English Championship club Middlesbrough for ruining Williams's FIFA World Cup dream.
The Dutch coach said 21-year-old Williams would have been a certain member of his squad had it not been for a pelvic injury, which plagued him for much of the season. Williams continued to play through the pain barrier for Middlesbrough, receiving injections to keep going, Verbeek said.
"He trained without confidence -- he could never train fully, he's not free to play and his recovery is not quick enough to make it. I'm disappointed he will not be in the final 23," he said.
Goalkeepers: Mark Schwarzer (Fulham/ENG), Adam Federici (Reading/ENG), Brad Jones (Middlesbrough/ENG).
Defenders: Scott Chipperfield (FC Basel/SUI), David Carney (FC Twente/NED), Lucas Neill (Galatasaray/TUR,captain), Michael Beauchamp (Al-Jazira/UAE), Craig Moore (no contract), Mark Milligan (JEF United/JPN), Luke Wilkshire (Dinamo Moscow/RUS).
Midfielders: Mark Bresciano (Palermo/ITA), Tim Cahill (Everton/ENG), Jason Culina (Gold Coast Utd/AUS), Brett Emerton (Blackburn Rovers/ENG), Richard Garcia (Hull City/ENG), Vince Grella (Blackburn Rovers/ENG), Brett Holman (AZ Alkmaar/NED), Mile Jedinak (Antalyaspor Kulubu/TUR), Carl Valeri (US Sassuolo Calcio/ITA), Dario Vidosic (FC Nurnberg/GER).
Strikers: Josh Kennedy (Nagoya Grampus/JPN), Harry Kewell (Galatasaray/TUR), Nikita Rukavytsya (FC Twente/NED).
*Please note that squad lists only become official after they have been submitted to and announced by FIFA.