Buddle, of the Los Angeles Galaxy MLS team, got his first marker just 2 minutes into the contest at Roodepoort, South Africa, then broke a 1-1 tie in the 31st minute when he scored on a header off a pass from Steve Cherundolo.
Herculez Gomez notched the third and final U.S. goal just before the final whistle.
Tim Cahill collected the only goal for Australia in the contest, which served as a tuneup for both teams before next week's World Cup in the African nation.
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