Leckie overcame close to two years' worth of hamstring injuries to force his way into Tony Popovic's squad for this year's tournament.
But the 35-year-old succumbed to a hamstring injury in Australia's second group game against the United States and watched the Socceroos' game against Paraguay before departing camp early.
"I think I handled it pretty good. Obviously disappointed and frustrated in the first moment, but I've experienced it enough now," Leckie said on Wednesday.
"I think it was nice to be able to stay at least for the third game to celebrate with the boys for getting out of the group.
"More the frustrating part was just that I actually felt very, very good.
"I had a long period over there of training and even in the game, didn't feel my hamstring at all. There were no signals to say there was something there, so it sort of came out of nowhere."
""There were a couple of days of sadness and then I was alright."
Leckie said the hamstring strain was enough to end his tournament, but it wasn't too serious, and the long A-League pre-season had him prepared.
Asked if he would be ready to go for City's October 17 opener against Auckland FC, Leckie said: "I'd like to think so."
While other players are already circling January's Asian Cup in their calendars, Leckie is refusing to look ahead to contending for selection for that tournament - which he missed through injury in 2024.
"Not necessarily," he said.
"I think for me, the most important thing is to to get myself fit and playing well for City.
"What's beyond, I don't want to think too far ahead. Although it's quite close, it still is very far, a lot of games to play."
The A-League Men and Women seasons could start without a collective bargaining agreement (CBA) locked away.
"We want a CBA deal done, and we think we've got to put it out there for APL to come to the table, and we hope that we can start the season with a CBA," City A-League Women captain Rebekah Stott said.
Leckie added: "We all want the future of the game to be in a good spot, and I guess that's where the negotiations are.
"And I think as of now, it's looking more promising that they'll come to something."
Neither Leckie nor Stott felt their teams had been affected by ongoing speculation around Melbourne City amid sister club Manchester City's financial scandal.
"Obviously aware of it, like everyone is," Leckie said.
"But although we're linked with Manchester City, we don't have much information, and it's nothing for us to, I guess, consider .
"What will be will be. We can't really control anything that happens. We've just got to continue doing what we're doing and prepare for the season."
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