Following a scouting mission to the UK, Arnold on Friday handed maiden senior call-ups to Middlesbrough winger Sammy Silvera, Ipswich defender Cameron Burgess and Charlton goalkeeper Ashley Maynard-Brewer.
Parma defender Alessandro Circati and Boro goalkeeper Tom Glover, who were both named but didn't play in June's friendly against Argentina, have also been selected in a youthful Socceroos squad.
Arnold would have called-up more emerging talent but injury prevented Portsmouth forward Kusini Yengi and Belgium-based left-back Jordan Bos joining the national team for the September 10 friendly in Dallas.
Eight other members of the squad have fewer than 10 caps in what points to a changing of the guard for the Socceroos.
Twelve of those present at last year's World Cup have retired or been overlooked due to injury or a lack of game-time.
Garang Kuol, Adjin Hrustic, Jason Cummings and Awer Mabil do not feature in Arnold's squad, while Aaron Mooy hung up his boots earlier this year.
It gives Australia a glimpse of what is to come at January's Asian Cup.
Silvera's displays under the tutelage of former Manchester United and England midfielder Michael Carrick at Middlesbrough have thrust him into contention.
"In the A-League he was hot and cold but he seems to be performing more (consistently) at a good level now," Arnold said of the former Central Coast Mariners player.
Burgess's selection comes with Harry Souttar struggling for minutes at Leicester and a long-term injury to Gianni Stensness.
Born in Aberdeen before spending his formative years in WA, the 27-year-old Burgess won youth caps for Australia and Scotland.
"We've watched him for about 12 months and I would've picked him for the Argentina game but he was injured," Arnold said.
"It's fantastic to have another left-footed centre back. He's 198cm, a big boy, very strong and he's playing at a very good level with Ipswich."
The Socceroos boss said Man City midfielder Alex Robertson, currently on loan at Portsmouth, was not selected to allow him to focus on club football.
Mathew Leckie and Aziz Behich are the only players selected from A-League clubs.
Arnold has frequently bemoaned the league's start date, this year on October 22, with Brandon Borrello, Jamie Maclaren and Craig Goodwin all overlooked.
"It hurts and damages the September and October (international) windows," Arnold said.
"It's the hardest thing to ring those players and tell them that they haven't been selected and it's not their fault. It's the domestic league and the structure that we have."
The one-off friendly against the world No.12 gives Arnold a chance to thrust his younger players into a high-pressure environment at the 80,000-seater AT&T Stadium where a pro-Mexican crowd is expected.
"We could strike these type of games in the next World Cup," Arnold said.
"This is where you learn the players who can deal with these type of moments and occasions."
The Socceroos have scheduled friendlies with New Zealand and England in October and have World Cup qualifiers in November, before their Asian Cup bid begins in January.
SOCCEROOS SQUAD (*uncapped).
Mat Ryan (c), Tom Glover*, Ashley Maynard-Brewer*; Nathaniel Atkinson, Aziz Behich, Cameron Burgess*, Alessandro Circati*, Milos Degenek, Kye Rowles, Harry Souttar, Ryan Strain; Keanu Baccus, Martin Boyle, Cammy Devlin, Denis Genreau, Jackson Irvine, Riley McGree, Connor Metcalfe, Aiden O'Neill, Sammy Silvera*; Nick D'Agostino, Mitch Duke, Mathew Leckie.
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