England 323 (Root 110, Stokes 58, Radaba 5-78, Morkel 3-76) and 77 for 3 beat South Africa 313 and 83 (Broad 6-17) by seven wickets
Stuart Broad left England in ecstasy in Johannesburg as he summoned the sort of great Test fast-bowling burst that has become his forte to deliver an unexpectedly rapid victory in the third Test and an unassailable 2-0 lead in the series.
South Africa were routed for 83 in 33.1 overs, leaving England needing only 74 for a victory, a task they undertook calmly, losing three wickets with the match well won. The final Test in Centurion next week will come amid considerable South African soul searching. Whatever the outcome, India will assume their No. 1 Test ranking.
Broad's sequence of 5 for 1 in 36 balls destroyed South Africa's top order in the first hour after lunch as 23 for 0 became 35 for 5. Remarkably, it was the seventh time in his Test career that he has taken five or more wickets in a spell. When he sees an opportunity he does not demur but shows an animalistic desire to seize the prize; when he runs hot the opposition are scalded.
He finished with 6 for 17 in 12.1 overs, not to be denied the final wicket when Faf du Plessis swung the ball onto his pad and, eyes lighting up, a sprint and dive claimed a one-handed catch in the middle of the pitch.
South Africa had suffered disturbing collapses in India, but this disintegration in front of their own supporters, and in the Bullring, too, where they have so often been at their most ferocious, will cause the greatest reverberations of all. Expectations that AB de Villiers' elevation to the captaincy would be South Africa's route to salvation have proven overly optimistic. Broad extinguished their guiding light for a fifth-ball duck and the Test turned in a trice.
This was South Africa's lowest total in a home Test since readmission and second lowest of all in that period, beaten only by their 79 against India on a turning surface in Nagpur in November. They have now failed to beat England in their last three home series, losing two of them.
A fluctuating Test, compelling from the outset, had been tantalisingly poised after the first innings, with England holding an insignificant 10-run advantage, but it was commandeered by Broad as South Africa lost eight wickets in the afternoon session. A big weekend crowd were stunned as the No 1-ranked side in the world were picked apart.
A muggy day had provided perfect conditions for swing bowling, the floodlights blazed, the pitch offered pace, bounce and increasing seam movement, and Broad responded to his opportunity voraciously. A great bowler or a bowler of great spells? Bowl enough of the latter and you begin to lay claim to the former. What was undeniable was that he passed Bob Willis's record of 325 Test wickets to go third on England's all-time list behind James Anderson and Ian Botham.
In the first innings, he was enervated by the stomach bug that had raged through the England camp, leaving the field on at least one occasion to be sick. Now his health had returned - his hair, stragglier than usual, the only reminder that he had been too unwell to attend to some of the niceties of life. He bowled with great intensity, hit an excellent length from a great height with resolve, his pace up to maximum.
Broad's first wicket, three overs into the afternoon, needed Dean Elgar to fend at a wide one, but that was enough to heighten his recognition of the opportunities on offer. Even the solitary single he conceded in his five-wicket burst came from a dropped catch offered by Stiaan van Zyl as Anderson failed to hang on at second slip. Van Zyl soon pushed a fullish ball to Ben Stokes at gully.
South Africa had banked upon setting loose a ferocious pace quartet on a Wanderers pitch possessing more grass than normal. Their inexperience meant they conceded to somebody better. Instead, it was Broad who was roused, reviving memories of his 8 for 15 to dismiss Australia for 60 in one spectacular session at Trent Bridge in August, or his five wickets in 16 balls against India on the same ground four years earlier.
If the openers were a satisfying starter, the main course - AB de Villiers and Hashim Amla in successive overs - was a gourmet dish served to a privileged few. It took a fine delivery to dismiss de Villiers for a five-ball duck, jagging back sharply for Jonny Bairstow to hold the inside edge.
Amla was the first of two batsmen to fall to a stunning catch by James Taylor at short leg - shrewdly positioned, it turned out, slightly more forward than usual. Taylor was slightly on the rise when he changed direction to clutch Amla's firm clip by his ankles. The little men, Taylor and Temba Bavuma, are perfectly designed for the role - instant response units, armed with fast reflexes, bravery and an ability to get down quickly from a low starting position.
Bavuma then played on for a duck, swaying back with an intention to leave but running the ball onto his stumps. Broad, who relishes the role on tour of the Bad Guy, signalled his five wickets to the crowd. When Faf du Plessis, struck on the shin, picked the ball up and tossed it back to him, he looked aghast, hands on hips, the very picture of theatrical villainy. In no mood to let go of the ball, he puffed out his cheeks and extended his spell to 10 overs before standing down with 5 for 14 to his name.
Amid all this, Anderson had glowered his way through an unrewarded spell, finding movement himself, but still looking out of sorts with the world. Instead it was Steven Finn and Stokes who offered initial support.
Dane Vilas fell to another outstanding catch by Taylor, another firm stroke, this time the fielder flinging himself to his right to intercept. Finn's first wicket was followed by two for Stokes, who also swung the ball lavishly, bowling the right-handed Chris Morris with one that came back, then finding outswing to the left-hander to silence Kagiso Rabada's brief flurry.
South Africa did not detain England overlong after tea, Anderson having Viljoen lbw before Broad's full-length dive left England on the brink of their first Test series victory overseas since they overcame India in 2012-13.
Rabada, a quality fast bowler in the making, had been somewhat overshadowed. But he had prospered in the morning in a manner that augers well for South Africa's future, taking his first took first five-wicket haul in Tests. Blessed with a smooth action and a calm head, he took three of England's last five wickets on the third morning as they added another 85 runs.
For all the praise directed towards Joe Root on the second day for one of the finest hundreds of his career, the Test had still been in the balance when play resumed. At 238 for 5, England trailed by 75 and Root himself did not stay long. He added only four to his overnight 106 when an airy drive against Rabada caused his downfall. Few would have anticipated that later in the day he would be at the crease once more, hitting the winning runs as England won the series.
David Hopps is a general editor at ESPNcricinfo @davidkhopps