Australia's record try-scorer has refused to rule-out his fellow countrymen, and the Lions next opponents, but he reckons the All Blacks are favourites to lift the William Webb Ellis trophy.
"You've got to look at New Zealand at home as favourites. That's certain. But the Wallabies are also coming good at the right time," said Campese.
"But there's a long way to go before then and to win a World Cup you need 15 players on the day to perform.
"In previous tournaments we've seen some players stand up and some don't under the intensity of the competition. That's what decides the winner."
Campese inspired Australia to World Cup glory in 1991 against England with six tries in six games.
But playing the Lions two year's earlier did not prove to be as enjoyable. Led by Finlay Calder, the Lions claimed an historic Test Series victory over the Wallabies.
During that tour Campese's famous second Test blunder, in which he lost the ball after attempting to run from his own try-line, cost Australia a crucial try which helped the famous tourists to victory.