South Africa lost six wickets for 32 on their way to a 73-run defeat to Australia in the third one-day international in Canberra.

The Proteas were 143-1 chasing Australia's 329-5, but several soft dismissals and a crucial spell from Mitchell Starc saw them bowled out with 5.3 overs remaining.

Aaron Finch was the mainstay of Australia's innings and he put on 118 for the first wicket alongside David Warner, who fell to Vurnon Philander shortly after passing fifty.

The hosts continued to build significant partnerships as both Shane Watson (40) and Steve Smith put on 50-plus stands with Finch.

The opener brought up his ton with a single off Imran Tahir, whose injury forced AB de Villiers into a rare bowl and the multi-faceted Proteas skipper surprised even himself when he bowled Finch for 109.

Smith started to cut loose and eight boundaries helped him to an unbeaten 73. Morne Morkel picked up the wickets of George Bailey (13) and Mitchell Marsh (22) but took some late punishment to end with 2-84.

Although South Africa nearly matched the Aussies for the first wicket as Quinton de Kock (47) and Hashim Amla piled on 108, they were reduced to 148-3 when Faf Du Plessis (17) and Rilee Rossouw (2) went cheaply.

Amla and De Villiers steadied the ship, and with their two most senior players at the crease at 224-3, the tourists were in a promising position before a lower-order collapse.

Josh Hazlewood bowled Amla for 102, while De Villiers followed two runs later for 52, and left-arm seamer Starc came back into the attack to dismiss David Miller (3), Philander [one] and Dale Steyn [12].

With Tahir unfit to bat, Farhaan Behardien was the last man out for 12 as Australia took a 2-1 series lead.