Cricket: Aussies hit unprecedented low after crippling collapse

Australia's Mitchell Starc, right, lays on the ground after failing to stop a South African ball from scoring 4 runs. Photo / AP

Australia's under-siege Test side are at risk of hitting an unprecedented low, having handed South Africa a series victory with yet another crippling batting collapse in Hobart.

Australia's dependence on Steve Smith was laid bare for the second time in the second Test at Bellerive, where the Proteas completed an innings-and-80-run win before lunch on day four - the home side's fifth straight Test defeat.

South Africa claimed an unassailable 2-0 lead in the series on Tuesday, rolling Australia for 161 at 11.53 AEDT to mark their third consecutive Test series win in Australia.

Further ignominy for Smith could come under lights at Adelaide Oval. Never before in the history of the sport has Australia been whitewashed in a Test series on home soil.

Based on how the pink ball hooped around in Adelaide last year, there's likely to be a result in the final Test that starts next Thursday.

The hosts tumbled towards a fifth straight Test loss during a collapse of 8-32 in 19.2 overs, with Kyle Abbott snaring six wickets and Kagiso Rabada striking four times in the stunning session.

It was the latest of many woeful batting performances in recent years that has left coach Darren Lehmann, selectors and Cricket Australia boss James Sutherland under immense pressure.

Selectors are expected to settle on a squad for the third Test later this week but changes are fully expected, with Adam Voges likely to be dropped.

Smith dug in, taking 40 minutes to score his first runs on day four, but would have been struck with a sense of deja vu as he watched Australia slip from 2-129 to 7-150.

The skipper was eventually caught behind on 31. Rain offered more resistance than Australia's batsmen, with the entire second day abandoned without a ball being bowled. Smith had finished 48 not out on day one, when Australia posted a paltry total of 85 after being sent in by Faf du Plessis.

It was the nation's lowest Test total on home soil since 1984.