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.
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.
Hughes, who averaged 46.60 in the Test series that finished on Sunday, timed his strokes sweetly, deploying his favoured cut shot whenever possible and compiled 14 boundaries.
"It is a good deck," Hughes said. "It flattened out beautifully.
"It was nice to get a few. My first game in the one-day format, to get to three figures is a dream come true. This is my favourite ground."
The leading run scorer in Australia's domestic one-day and Twenty20 tournaments, Finch was more circumspect and made his way to 16 from 28 balls before edging Ajantha Mendis to Chandimal.
Khawaja's run out brought Bailey to the crease with the score on 72-2 and Australia's Twenty20 captain took on a bowling attack bolstered since the end of the Test series by Lasith Malinga and Mendis.
He hit eight fours and smacked Jeevan Mendis for a big six high over long on.
Australia slipped from 212-2 to 248-5 as Hughes edged Malinga to Chandimal, Bailey pulled Angelo Mathews to Jeevan Mendis at deep midwicket and Glenn Maxwell departed for 5.
But the experienced Hussey grasped the finisher's role with a whirlwind innings that included 20 runs and a wide off the last over from Ajantha Mendis.
Sri Lanka were never in a position to challenge as wickets fell steadily thanks to some poor shot selection and sharp fielding.
Upal Thuranga nicked Mitchell Starc to Brad Haddin for just 1 and it was 17-2 when Mahela Jayawardene edged McKay to Finch at first slip for 5.
Chandimal and Dilshan did their best to rebuild but Khawaja's direct hit, another by Maxwell that accounted for Mathews (12) and then the run out of Lahiru Thirimanne (0) by the combined efforts of Maxwell and Haddin made it 128-5.
There was no way back for Sri Lanka and McKay finally winkled out Chandimal before mopping up the tail.
Aaron Finch c Chandimal b Mendis 16
Phil Hughes c Chandimal b Malinga 112
Usman Khawaja run out 3
George Bailey c Jeevan Mendis b Mathews 89
David Hussey not out 60
Glenn Maxwell c Ajantha Mendis b Kulasekera 5
Brad Haddin not out 10
Extras: (B-2, LB-3, W-5) 10
Total: (For five wickets in 50 overs) 305
Fall of wickets: 1-53, 2-72, 3-212, 4-241, 5-248.
Bowling: Nuwan Kulasekera 10-0-53-1, Lasith Malinga 10-1-61-1, Angelo Mathews 8-0-46-1, Ajantha Mendis 10-0-62-1, Tillakaratne Dilshan 4-0-17-0, Thisara Perera 4-0-28-0, Jeevan Mendis 4-0-33-0.
U Tharanga c Haddin b Starc 1
T Dilshan run out 51
M Jayawardene c Finch b McKay 5
D Chandimal c Haddin b McKay 73
Mathews run out 12
L Thirimanne run out 0
J Mendis c Bailey b Johnson 20
T Perera c Bailey b Johnson 4
N Kulasekara c Bailey b McKay 18
L Malinga not out 1
A Mendis c Haddin b McKay 0
Extras: (b-2, lb-2, w-9) 13
Total: (All out; 40 overs) 198
Fall of wickets: 1-8, 2-17, 3-111, 4-128, 5-128, 6-167, 7-169, 8-194, 9-198.
Bowling: Starc 6-0-25-1, McKay 8-0-33-4, Johnson 9-1-43-2, Doherty 8-0-41-0, Maxwell 4-0-28-0, Hussey 5-0-24-0.
Photograph: Getty Images