James Anderson wrecked South Africa's batting order with a career-best performance as England won the fourth one-day international by seven wickets at St George's Park on Sunday.
The fast bowler took five wickets for 23 as South Africa were bowled out for 119, their lowest total in a one-day international in their own country.
"Jimmy Anderson was outstanding in the way he created pressure but then bowled wicket-taking deliveries as well," said England captain Andrew Strauss.
Jonathan Trott and Strauss put on 74 for England's first wicket. The tourists suffered a wobble when three wickets fell for nine runs but cruised to victory with 18.4 overs to spare. Trott finished with 52 not out.
It was a remarkable turnaround for England, who conceded 354 runs when they lost the third international by 112 runs in Cape Town two days earlier.
The win gave England an unbeatable 2-1 lead in the series. The final match will be played in Durban on Friday.
South African captain Graeme Smith was dismissed by Stuart Broad off the eighth ball of the match and his side were unable to recover.
Smith gambled by batting first in overcast conditions on a pitch with slightly more grass than usual and the early loss of their leading batsman exposed a lengthy tail.
England's bowling was accurate and the South Africans failed to adapt to a slower pitch than that on which they prospered in Cape Town.
"It was probably a good toss to lose," admitted Strauss. "But I was very pleased with the way the bowlers adapted to those conditions. We were very accurate today."
Strauss said that after Friday's heavy defeat the team had "a good chat".
He said: "We wanted to clarify our plans against their batsmen, which we got pretty much spot on."
Anderson bowled superbly in two spells and benefited from bold captaincy by Strauss. After a first spell of two for 17 in six overs, Strauss brought back his strike bowler in the 21st over to press home his side's advantage.
Anderson responded by taking three more wickets and completed his stint by the end of the 27th over. By then, South Africa had lost seven wickets for 85 runs.
Tim Bresnan provided excellent support for Anderson, taking one for 15 in an unbroken spell of eight overs.
He took the key wicket of AB de Villiers, who made a century in Cape Town and was looking in good form until he was leg before to Bresnan for 22.
Alviro Petersen, the least experienced of the South African top order, was the only batsman to shine, making 51 off 79 balls before he was the last man out. It was Petersen's third successive half-century in the series.
"We didn't assess conditions well enough this morning," said Smith. "If we had got 220 or 240 it would have been a really good target to defend. It was a disappointing performance."
Strauss survived a confident appeal for a catch behind off Morne Morkel when he was on 12 but otherwise he and Trott batted comfortably before Strauss fell to recalled off-spinner Johan Botha for 32.
Kevin Pietersen again failed to find his best form. He was dropped at long leg by Morne Morkel off Ryan McLaren before he had scored and made only three before he chipped Botha to midwicket.
Paul Collingwood failed for the first time in the series when he was caught behind off McLaren for two before Trott and Eoin Morgan took England to victory in an unbeaten stand of 38.
