Teenage striker Garang Kuol, who recently signed for Newcastle United, was included Tuesday in Australia's squad for the World Cup, but influential midfielder Tom Rogic missed out.
Japan-based striker Adam Taggart -— who has scored six goals in 16 Socceroos appearances -- was another surprise omission despite being a stalwart of their qualifying campaign.
That opened the door to the Central Coast Mariners' Kuol, who makes the switch to St James' Park in January.
Kuol, 18, made his international debut for Australia against New Zealand in September, becoming the youngest Socceroo since Harry Kewell in 1996.
But he has yet to start a game for his A-League side, with Arnold likely to use him as an impact player off the bench.
Former Celtic star Rogic withdrew just before Australia's crunch World Cup qualifiers in May, citing personal reasons, and has since struggled to make an impact at new club West Bromwich Albion.
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Veteran goalkeeper Mitch Langerak was also overlooked despite being in career-best form for J-League club Nagoya Grampus and widely seen as the number two behind skipper Mat Ryan.
Instead, Arnold opted for Danny Vukovic, along with Andrew Redmayne, a hero in Australia's penalty shootout win over Peru that confirmed their place in Qatar.
Australia are in Group D and open their campaign against France before meeting Tunisia and Denmark.
Goalkeepers: Mathew Ryan (FC Copenhagen/DEN), Andrew Redmayne (Sydney FC/AUS), Danny Vukovic (Central Coast Mariners/AUS)
Defenders: Aziz Behich (Dundee Utd/SCO), Milos Degenek (Columbus Crew/USA), Thomas Deng (Aibirex Niigata/JPN), Joel King (Odense Boldklub/DEN), Nathaniel Atkinson (Hearts/SCO), Fran Karacic (Brescia/ITA), Harry Souttar (Stoke City/ENG), Kye Rowles (Hearts/SCO), Craig Goodwin (Adelaide United/AUS)
Midfielders: Aaron Mooy (Celtic/SCO), Jackson Irvine (St Pauli/GER), Ajdin Hrustic (Hellas Verona/ITA), Bailey Wright (Sunderland/ENG), Cameron Devlin (Hearts/SCO), Riley McGree (Middlesbrough/ENG), Keanu Baccus (St Mirren/SCO)
Forwards: Awer Mabil (Cadiz/ESP), Mathew Leckie (Melbourne City), Martin Boyle (Hibernian/SCO), James Maclaren (Melbourne City), Jason Cummings (Central Coast Mariners), Mitchell Duke (Fagiano Okayama/JPN), Garang Kuol (Central Coast Mariners/AUS)