South Africa heaped further misery on the embattled Australians, easing to a crushing win by an innings and 80 runs as they wrapped up the three-Test series in Hobart.

If Australia's first-innings capitulation was not bad enough, the hosts crumbled again on day four of the second Test to hand the South Africans an unassailable 2-0 series lead.

Australia resumed at 121-2 on day four but Kyle Abbott (6-77) and Kagiso Rabada (4-34) tore through the batting order to wrap up the match before lunch on Tuesday.

Usman Khawaja and under-fire captain Steve Smith returned to the crease optimistic of forcing a draw after staging a fightback on Monday, but Australia's hopes of avoiding defeat were quickly dashed.

Seem and swing were on the menu early, and Abbott was the first bowler to benefit, dismissing Khawaja for 64.

Abbott's delivery angled away from Khawaja, who edged behind to Quinton De Cock at chest-height.

Despite Smith surviving and successfully reviewing a caught-behind decision at 130-3, Khawaja's departure triggered a stunning collapse.

Abbott struck again, claiming the wicket of Adam Voges (2). The veteran batsman was caught between pulling and leaving, misjudging the length as the ball nicked the bat.

Callum Ferguson (1) followed five runs later with the Aussies reeling at 140-5. He was another batsman caught in two minds, not sure whether to duck or sway away, and in the end Rabada's delivery brushed his glove and carried through to Dean Elgar at third slip.

Peter Nevill (6) and Test debutant Joe Mennie (0) were quickly sent back to the pavilion, falling victim to Rabada in the same over.

Smith was Australia's last form of resistance and once he departed after edging to De Kock, it all but ended the contest as South Africa finished off the tail, the hosts losing 32-8.

The third and final Test of the series is in Adelaide beginning November 24.