The two-time champions won just four of 13 Tests last year, but Cheika - who led Australia to the 2015 final - once again shrugged off criticism.
"We will be in good shape when we need to be," he said at the Australian embassy in Tokyo.
"It's going to be an open World Cup for sure - not just because of how the teams have performed leading up to here, but also because it's in Japan.
"It's going to be very different, a different atmosphere at the games," added Cheika, whose side have slipped to sixth in the world since he steered them to the 2015 World Cup final.
"We've got a bit to do before then, but the players can't wait and the lucky ones who get picked can't wait to get on the plane."
Australia take on Fiji in Sapporo on September 21 in their Pool D opener, before facing Six Nations grand slam winners Wales, Uruguay and Georgia.
World Cup winners in 1991 and 1999, the Wallabies have done little in the run-up to this year's tournament to suggest they can capture a third title.
But Australia's new director of rugby Scott Johnson last week expressed confidence that Cheika's players were "not a million miles off" being able to get on a roll and upset the favourites.
"We have as much chance as anyone else," said Johnson. "Our rugby DNA is acumen and skill, and 'Cheik' has got great drive, great passion to get a team going good."
Cheika had his players running up steep hills in a punishing January fitness camp in an attempt to knock them into shape for a brutal World Cup year.
However, with bitter rivals New Zealand again the team to beat as they chase an unprecedented third successive World Cup, Australia are dealing with backroom changes after the sacking of attack coach Stephen Larkham.
"There were changes on and off the field I think we needed to make to get the best possible outcome," said Cheika, who last month hit out at his "over-dramatic" critics.
"Sometimes you've got to make hard decisions - they're very difficult but it was the right thing to do to move us into a space where we could get a different outcome."
Cheika appeared relieved when journalists steered questions away from the Wallabies by asking for his thoughts on the demise of the Tokyo-based Sunwolves, who were axed from Super Rugby six months before Japan hosts the World Cup.
"Personally I'm very disappointed," said the 52-year-old.
"They play good rugby, they're entertaining - and that's what we do. We're there to entertain and give people value for money so I think it's very disappointing they're (no longer) involved."