Four years ago Volpato, now with Serie A side Sassuolo, rejected the advances of former manager Graham Arnold to be a part of the Socceroos' squad for the World Cup in Qatar.
But Popovic revealed the attacking midfielder, who was born in Sydney and has represented the Azzurri at youth level, had warmed to the idea of playing international football for Australia.
Popovic has always stressed he would never make a "sales pitch" to a player who is undecided on their international future.
The Socceroos boss and assistant coach Paul Okon met with Volpato in Italy last month and are waiting to see if he commits ahead of this year's World Cup in North America.
"We're not selling the shirt," said Popovic, whose side face Cameroon and Curacao in World Cup warm-up friendlies in Sydney and Melbourne this month.
"What's probably changed is that 'Paulo' has been in touch with him regularly since October.
"On this occasion, he indicated that he'd be interested in a discussion about playing for Australia - and once he indicated that to Paulo and I was in Europe, we both went over to see him and have chat.
"There were no ultimatums or any pressure - it was a discussion, and if he wants to play for Australia, whether that's, let's say, three months, six months, a year … they're young men, you have to respect the decisions they have to make.
"He's indicated he's open to the idea, now the rest is just for him to decide."
Volpato's potential availability should hearten Popovic, who also acknowledged the form of Ante Suto, an uncapped Croatian-Australia who is flying in Scotland with Hibernian.
Popovic's squad has taken several hits ahead of this month's friendlies, particularly up front, where Nick D'Agostino, Mohamed Toure and Kusini Yengi are all sidelined.
The coach confirmed Yengi will miss up to three months after sustaining a quad injury in Japan.
Right-back Lewis Miller is out of the tournament.
Meanwhile, centre back Harry Souttar is yet to return to club football with Leicester after picking up a knee issue this year following a 12-month lay-off with an achilles injury.
"He's on the pitch now with the team, so that's progress," Popovic said.
"He (Souttar) is in a difficult situation (with a club that is) fighting relegation at the moment, there's a new manager, so hopefully Harry can get some game time soon."
As well as the players already unavailable, Popovic is keeping a watchful eye on the condition of Jackson Irvine.
The influential midfielder was ruled out indefinitely by club side St Pauli in January, but has since returned to help in his side's battle against Bundesliga relegation.
"It will be an ongoing foot issue that he'll have to manage in the short term, and we'll have to see whether that can be managed all the way through to the World Cup," Popovic said.
"It's basically day by day, week by week.
"In January, I thought he's out, last month I still thought the same.
"Now we're at this stage and he's still fit, healthy and playing really well."
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