Australia, who start the Ashes series at the end of the month, never looked like reaching their initial victory target of 244 in 39 overs or the 240 in 38 overs they were handed under the Duckworth-Lewis method after rain stopped play for a third time.
Impressive opener Upul Tharanga contributed an unbeaten 86 to Sri Lanka's 213 for three, which they achieved in 41.1 overs as showers interrupted the action for a total of nearly three hours.
Shane Watson (40), Cameron White (35) and Steven Smith (33) offered the faintest glimmer of hope for the Australians but it was always going to be an uphill battle and they crumbled to 210 all out.
The attendance of 11,495 was the lowest crowd for a one-day international at the Sydney Cricket Ground for 27 years and most were supporting Sri Lanka.
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