The veteran, who famously scored the winner over Denmark that sent Australia to the round of 16 in Qatar, is heading to his fourth World Cup.
Australia are in Group D and will play Turkey in Vancouver on June 14, the United States in Seattle six days later then Paraguay in Santa Clara on June 26 (all dates AEST).
The Socceroos are again underdogs but Leckie believes they can still do something special.
"The belief's always been there, I think it's a big driver in what we do," Leckie said.
"Away from the change room and everyone here, a lot of people expect us to finish bottom of our group, and it was the case in Qatar.
"But we're very aware that if you put two sheets of paper in front of the teams, on paper the other teams are probably stronger.
"But I think us as a collective is the reason why we always can compete, and were able to do what we did in Qatar.
"And we don't see why it should be any different here, and we also think we can do the same, if not better this time around."
Leckie and skipper Maty Ryan will join Tim Cahill and Mark Milligan as the Socceroos' only four-time World Cup attendees.
"It's quite unbelievable to be in the same position as players like them," Leckie said.Â
"So it's something that I probably can look back on in the future and be super proud of, but there's still a long way to go."
The 35-year-old played his first international since June 2024, following a horror injury run, in Saturday's 1-0 loss to Mexico.
He has enjoyed getting to know young teammates that either emerged or established themselves during his absence, like Irankunda, Mohamed Toure and Lucas Herrington.
Leckie, who featured at his first World Cup as a 23-year-old in 2014, is enjoying watching them blossom.
"They're obviously super-talented players, they're doing well, even overseas," Leckie said.
"... I feel sometimes when you're young, you just go into a tournament like this, there's not very little thought, and it's just you go out and do your thing. And that can be the key, I guess, not overthink things, and just go out there.
"What's important is they're here for a reason.
"They're good enough, that's why they're here, and if they can just go into the tournament and just keep doing what they've been doing, I'm sure they can show the world how good of players they are."
Irankunda and Volpato were in the thick of an entertaining attacking drill at Monday's training.
Dynamo Irankunda reminded everyone of his quality with some lethal shooting and forward bursts, where uncapped striker Tete Yengi and Volpato were also involved.
The 20-year-old had a scare at one point when he slipped, favoured his left foot then stood on the sidelines for a short time, but later returned to the fray and picked up where he left off.
Sassuolo winger Volpato joined training for the first time since his defection from Italy and showed some flashes of his class on the ball.
"Obviously just today, but he looked really good, sharp, tidy," Leckie said.
"So he's another left footer addition, which is always nice. So, yeah, it'll be interesting to see."
Players that started against Mexico were involved early then sat out the second half ahead of this Saturday's friendly against Switzerland in San Diego.
