Wednesday's draw in Kyoto saw Australia grouped with Wales, Georgia and two other yet to be decided teams from Oceania and American qualifying in Pool D.
Compared to the 2015 tournament, where Australia were lumped in a 'group of death' with Wales and hosts England, the third-ranked Wallabies' path to the quarter-finals in Japan has been described as a "dream draw" by local media.
Cheika, however, is having none of it.
"They won't be easy games," Cheika, who guided the Wallabies to the final in England, told Australian media from Kyoto.
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"When you're standing out there and you're singing the anthem, it's 0-0. All bets are off.
"The minute you start thinking like that is the minute you're dead in the water."
Australia thrashed Wales 32-8 at their home Millennium stadium in Cardiff last year and also beat them in pool play during the last World Cup in England, part of a 12-match winning streak against the Welsh dating back to 2007.
Georgia are something of an unknown quantity as the Wallabies have never played them. They have qualified for the last four World Cups and impressed at the 2015 tournament where they upset Tonga and defeated Namibia.
"They are a team being run by a few Kiwi lads over there and they're on the up and up," Cheika said of the former Soviet republic coached by former New Zealand professional Milton Haig.
"They have some strong forward play and some gas out wide, so between now and 2019 we're going to have to learn a bit about them."
A rebuilding Australia were swept 3-0 in separate series against world champions New Zealand and England last year, and the current struggles of the nation's Super Rugby sides have sparked dire predictions for the Wallabies' prospects against the All Blacks in the annual Rugby Championship.
But Cheika has downplayed the concerns, tipping his new generation of players to be competitive come World Cup time.
"You can plan the lay of the land, know the teams you're playing, know who the potential cross-over teams are, you can do the homework but at the end of the day it's all about how we play," he said.
"You have to win seven games to get there.
"If you look at the 2015 Rugby World Cup, we came up short in one half of one game at the end, and that cost us from winning seven in a row.
"So we need to change and get better so we can win those seven games in a row when the time comes."
(Reporting by Ian Ransom; Editing by Peter Rutherford)
