Smith's turning point of Test series

With South Africa on track to beat Australia 3-1, former Proteas captain Graeme Smith said it was AB de Villiers' masterful century at St George's Park that swung the series the hosts' way.

Entering Port Elizabeth one-nil down having been beaten by 118 runs in the opening Test at Kingsmead, the Proteas bundled Australia out for 243 before de Villiers delivered the hosts a match-winning lead.

De Villiers' chanceless 126no was his first Test century in three years but one of his most important, and with spearhead Kagiso Rabada capturing 11 wickets, the hosts stormed to an emphatic, series-levelling win.

De Villiers' classic in Durban was the second Proteas century of the series after Aiden Markram's 143 in Durban, and since the second Test the hosts have registered two more centuries – Dean Elgar's marathon 141 in Cape Town and Markram again, with 152 in the first innings at The Wanderers.

In complete contrast, Australia have not had one player reach triple figures on tour. Mitchell Marsh's 96 in the first Test is the closest an Australian has come.

Australia's batting woes are reflected in the series statistics to date, which reveal suspended opener Cameron Bancroft as the visitors' leading run-scorer with 223 runs at 37.16, the only Australian in the top five run-getters of the tour.

Should no Australian post a century in the fourth and final innings of this Test, it will be the first time in 48 years an Australian side has failed to post an individual hundred in a Test series with at least four matches.

That series in 1970, coincidentally, is the last time South Africa beat Australia on home soil, a 48-year streak that looks set to be snapped at some point in the next two days.

The disparity in performance of the opposing batting units is where the series has been won by South Africa, says Smith.

"I think there was a moment in that second Test match where de Villiers's hundred turned everything for the South Africans," Smith told cricket.com.au on Sunday.

"It got them a lead and then Rabada stepped up.

"If you break the series down, I think in particular, (South Africa) have batted much better than the Australians throughout the series.

"The top run-getters are South African and the only guy in the top five is Bancroft from an Australian perspective.

"That's been the big difference. I said before the series, whoever scores the most runs with these two attacks will ultimately end up winning the series and that's what's going to happen.

"Not one hundred from an Australian on tour and I think that's telling."

South Africa's bowlers have played their part too in driving the Proteas to the brink of an historic victory.

Rabada has 23 wickets in three Tests with one innings left, and is just three wickets off equalling Mike Proctor's record for the most wickets against Australia in a four-Test series, which was set, perhaps not coincidentally, in 1970.

But Smith says it hasn't just been Rabada but the Proteas attack as a whole that has seen them out-bowl their rivals.

"I think they've bowled well as a unit," Smith said. "There's been spells where the Aussies have bowled really well individually, but I think South Africa has been able to string it together as a unit, as a pair and a partnership and ultimately struck from both ends at times.

"That has been the difference."

Qantas tour of South Africa

South Africa squad: Faf du Plessis (c), Hashim Amla, Temba Bavuma, Theunis de Bruyn, Dean Elgar, Heinrich Klaasen, Quinton de Kock, Keshav Maharaj, Aiden Markram, Morne Morkel, Chris Morris, Wiaan Mulder, Lungi Ngidi, Duanne Olivier, Vernon Philander, Kagiso Rabada, AB de Villiers.

Australia squad: Joe Burns, Pat Cummins, Peter Handscomb, Josh Hazlewood, Jon Holland, Usman Khawaja, Nathan Lyon, Mitchell Marsh, Shaun Marsh, Glenn Maxwell, Tim Paine, Matt Renshaw, Jhye Richardson, Chadd Sayers, Mitchell Starc.

Warm-up match: Australia beat South Africa A by five wickets. Report, highlights

First Test Australia won by 118 runs. Scorecard

Second Test South Africa won by six wickets. Scorecard

Third Test South Africa won by 322 runs. Scorecard

Fourth Test Wanderers, Johannesburg, March 30-April 3. Live coverage