Australia outclass India in opener
The top-ranked team in the competition were barely troubled by the bottom-ranked side with Harry Kewell and Brett Holman also scoring as Australia dominated from start to finish.
Cahill fired Australia into the lead after 11 minutes, Kewell doubled the lead with a left-foot drive after 25, and Holman headed the third at the end of the first half.
Cahill scored his second and Australia's fourth after 64 minutes with a typically excellent header from a Luke Wilkshire cross on an afternoon when Australian goalkeeper Mark Schwarzer only had to make one serious save, thwarting striker Sunil Chhetri six minutes from time.
The game was the first official meeting between the two countries since India beat Australia 7-1 in a friendly in Melbourne 55 years ago, although the two old British colonies have shared a healthy rivalry in cricket, hockey and tennis down the years.
In football terms at least, Australia are now very much the masters, coming into the competition as Asia's top-ranked team at 26th in FIFA's world standings, while India are ranked 23rd in Asia, the lowest in competition, and 142nd worldwide.
It did not take long for Holger Osieck's men to assert their authority with Cahill opening the scoring.
The Australians, with seven players in the starting line-up with experience of the English Premier League, were far sharper, fitter and quicker with the ball.
India had the more vociferous fans who created a lively atmosphere in the sleek modern stadium, but their team failed to make any significant impact and despite some initial probings from Climax Lawrence and Steven Dias in the opening spell, there was never a hint of an upset.
Schwarzer only had one easy effort to deal with from Surkumar Singh in the first half before a late intervention to stop the onrushing Chhetri - with the help of Lucas Neill - near the end.
The match was good as over as a contest after 25 minutes when the Indian defence generously conceded Kewell time and space and he picked his spot with a sweetly struck 25-metre drive that easily beat India keeper Subrata Paul to make it 2-0.
With the game fast resembling the sort of training match that top sides play against amateurs in the build-up to major tournaments, Australia made it 3-0 in first half stoppage-time when Paul was beaten by another Emerton cross allowing Holman to powerfully head home.
Cahill added the fourth midway through the second half and while Australia did not exactly run up a cricket score against their old rivals, they seemed content to declare at four goals.