Sassuolo playmaker Volpato, 22, headlines Australia's 26-man squad along with 25-year-old uncapped striker Tete Yengi - with both players earning World Cup selection before their respective debuts.
But it was heartbreak for veteran forward Martin Boyle, defender Kye Rowles - a starter in 2022 - forward Brandon Borrello and goalkeeper Joe Gauci, who were all cut.
Boyle was injured ahead of Qatar and again falls agonisingly short of playing at a World Cup.
Volpato knocked back Graham Arnold's pitch to join Australia's 2022 World Cup squad, then in March said he was waiting for a call-up from Italy's senior team, before his change of heart.
Sassuolo winger Volpato, 22, arrived in camp on Saturday morning (local time) - too late to feature in that night's 1-0 loss to Mexico - after switching his allegiance.
"There's a lot of growth and potential still there, which pretty much sums up a lot of our players at the moment," Popovic said of Volpato.
Skipper Mat Ryan and veteran Mathew Leckie head to a fourth World Cup, joining Tim Cahill and Mark Milligan in that rare group.
But they are the senior figures in a squad that features 17 players selected for their first cup, and eight players aged 23 or under, including 18-year-old centre-back Lucas Herrington.
"Without a doubt he deserves to be here," Popovic said.
Star defenders Alessandro Circati and Jordy Bos and dynamic attackers Nestory Irankunda and Mohamed Toure are also in that category, along with young midfielder Paul Okon-Engstler.
Popovic could see that core group growing together - like the Socceroos team he played in, but refused to "water down expectations" or say any were there purely with an eye to future tournaments.
"Will they be better in four and eight years? Without a doubt, but that's not to say they're not good enough now. If they weren't, I wouldn't play them, and I wouldn't have them in the squad," he said.
Popovic later added: "None of these boys are here to ... just sit on the side and not be involved. I want them all to give me a headache every week, and I believe in these young boys.
"I think they should believe in themselves more, and I know that will come with time.
"But they should feel assured and confident that they have a coach that believes in them, and that's why they're selected, and they know they are selected for this World Cup
"They're not selected for future ones, they're selected for this one."
The Socceroos play their final warm-up game against Switzerland on June 6 (June 7 AEST) in San Diego.
They then face Group D opponents Turkey in Vancouver on June 13 (June 14 AEST), the United States in Seattle six days later then Paraguay in Santa Clara on June 25 (June 26 AEST).
Yengi, younger brother of fellow Socceroo Kusini Yengi, impressed at Japanese club Machida Zelvia, on loan from Scottish outfit Livingston.
Harry Souttar and Leckie were selected after overcoming injury to make their first Socceroos appearances since 2024 in the Mexico friendly.
Aziz Behich, Jackson Irvine and Milos Degenek reach their third World Cup.
SOCCEROOS WORLD CUP SQUAD:
Goalkeepers: Patrick Beach*, Paul Izzo*, Mat Ryan
Defenders: Aziz Behich, Jordan Bos*, Cameron Burgess*, Alessandro Circati*, Milos Degenek, Jason Geria*, Lucas Herrington*, Jacob Italiano*, Harry Souttar, Kai Trewin*
Midfielders: Cameron Devlin, Jackson Irvine, Connor Metcalfe*, Mathew Leckie, Paul Okon-Engstler*, Aiden O'Neill*
Forwards: Ajdin Hrustic, Nestory Irankunda*, Awer Mabil, Mohamed Toure*, Nishan Velupillay*, Cristian Volpato*, Tete Yengi*
* First World Cup selection
