South Africa crushed Australia by an innings and 80 runs to win the second Test at Hobart and clinch their their third successive Test series Down Under on Tuesday.
The Australians suffered yet another batting collapse in their second innings which resulted in their heavy defeat to the visitors.
The Proteas bowled out the home side for 161 before lunch on the fourth day, taking their last eight wickets for 32 in 116 balls after routing Australia for 85 in the first innings.
The latest overpowering victory followed a 177-run win against Smith's shattered team in the first Perth Test, with South Africa emulating the intimidating West Indies teams of the 1980-1990s with three straight series wins in Australia.
"This cricket team is a tough team to get a win against them on their home soil," said South African captain Faf du Plessis.
"So to come here and do it is special for us. To win a series 2-0 with one game to play, I am very proud of the way the team is moving forward."
The second innings destruction heaped more pressure on Smith and Lehmann and increased calls for significant team changes for the final day-night Test against the tourists in Adelaide next week.
It was Australia's fifth consecutive Test defeat this year, after also losing all three Tests in Sri Lanka in August.
"We have to find a way to be a bit more resilient. It seems at the moment, regardless of what the ball is doing, we need to find a way to hit it better," said Smith.
"We need to find a way to be successful, because what we are doing at the moment is not working."
The Australians fell apart again on Tuesday, losing theirlast eight wickets with all the apparent weaknesses againexposed by potent South African pace bowling.
Kyle Abbott and Kagiso Rabada led the rampage with Abbott taking six for 77 and young gun Rabada four for 34.
Once Usman Khawaja was out just 20 minutes into thefourth day, the wickets continued to tumble. Khawaja was twice beaten by Abbott's movement off thepitch before he went for a cut on the last ball of the overand nicked to wicketkeeper Quinton de Kock for 64.
It was a body blow for the Australian hopes of salvagingthe Test so early into the fourth day and ended a 50-run standwith Smith. It brought Adam Voges to the crease under immensepressure to save his faltering Test career after a highestscore of 47 in his last 10 innings.
But Voges' self-doubt showed through when he tried towithdraw from at attempted pull shot only to glide adeflection to JP Duminy in the gully for two after scoring aduck in the first innings.
Voges trudged off the field after scores of 0 and 2,fearing his Test career was over at the age of 37.
Callum Ferguson was the victim of another ugly dismissal,bending to evade Rabada only to glove to Dean Elgar at thirdslip for one after scoring three in the first innings.
Wicketkeeper Peter Nevill was the next to go, failing toget out of the way of a Rabada bouncer and gloving to Duminy in the gully for six, while Joe Mennie lasted just two ballsbefore he was leg before to Rabada.