The home side slumped to 54 for four before Michael Clarke and Mike Hussey again came to the rescue to help them build a competitive total.
Hussey held the innings together with an unbeaten 64, while Clarke has been the one Australian batsman in form in the tri-series and made 50, the pair putting on 90 for the fifth wicket mainly through brilliant running.
It wasn't until Clarke hit a six and a four in successive balls from Lasith Malinga in the 38th over that the Australian run rate climbed above three.
The Sri Lankans won the toss and boldly elected to bowl first, concerned that the heavy skies could lead to the match being shortened.
Although the rain held off, their decision was rewarded when disciplined bowling again undone some of Australia's star batsmen.
The rot started early for the Australians, with opener Adam Gilchrist advancing down the track and being clean bowled for six during an impressive opening spell by fellow veteran Chaminda Vaas (1-34).
Matthew Hayde