Australian pacemen Michael Kasprowicz and Jason Gillespie took four wickets each to rip through the United States and set up a nine wicket win in the Champions Trophy match at the Rose Bowl, Southampton on Monday.
Adam Gilchrist then smashed 24 not out from 25 balls, charging down the wicket in the first over, as Australia reached their target of 66 in 7.5 overs.
The quickfire victory gave them a better net run rate than New Zealand, who beat the rank outsiders by 210 runs on Friday, and the statistic could become important if the final Group A clash between the Antipodean rivals is washed out.
Matthew Hayden edged a wild swipe behind for 23 to give Howard Johnson a prize wicket while Charles Reid dropped a caught-and-bowled chance off Gilchrist.
Kasprowicz earlier grabbed four for 14 and Gillespie four for 15 to limit the United States to 65, the lowest total in Champions Trophy history, in just 24 overs.
Only Steve Massiah (23) managed to make double figures although the U.S. showed some fight against the world's most potent attack.
They were not helped by 42-year-old former West Indies batsman Clayton Lambert being ruled out with injury.
Brett Lee started the demolition by bowling opener Mark Johnson for a duck second ball before Michael Clarke dropped a chance in the slips off Leon Romero next delivery.
Romero was run out by Damien Martyn next over, however, unintentionally blocked by bowler Glenn McGrath going for a dubious run.
McGrath, 34, returned to the Australia attack for their first game in the 12-team tournament but failed to take a wicket.