Phil Hughes became the first Australian to score a century on his one-day international debut as he powered the side to a 107-run win over Sri Lanka on Friday.
Hughes hit 112 and stand-in captain George Bailey struck 89 before David Hussey smashed 60 not out off 34 balls to turn a good total into a commanding 305-5 on a flat MCG wicket.
Dinesh Chandimal kept Sri Lanka in contention with a belligerent 73 but four wickets from Clint McKay and some superb fielding, including three run-outs, restricted the tourists to 198 in reply.
Victory ended a three-match losing streak against Sri Lanka at the MCG.
Australia, who won the test series 3-0, lead the five-match ODI series 1-0 with the second game on Sunday in Adelaide.
Sri Lanka could be without Chandimal for that game after the wicketkeeper, one of the few success stories of a one-sided test series, had to have repeated on-field treatment to what looked like a hamstring problem.
His mobility steadily decreased after he had his thigh bandaged.
Australia, though, can be happy with the way an inexperienced line-up coped without rested captain Michael Clarke and the omitted Mike Hussey.
Opener Aaron Finch and number three Usman Khawaja managed just 16 and three respectively after Australia won the toss but Hughes put on 140 for the third wicket alongside Bailey at the rate of a run a ball.
Khawaja later compensated for his failure - run out when he failed to ground the bat - with a direct hit from mid-off to run out the dangerous Tillakaratne Dilshan for 51.