England raced to a landslide victory at St George's on the back of James Anderson's maiden five-wicket haul to take an unbeatable 2-1 one-day series lead over South Africa.
The margin of seven wickets told its own accurate story on a day when everything went right for England from the moment home captain Graeme Smith chose to bat first under light cloud cover.
With miserable weather forecast for Durban, the venue for the only remaining fixture, the tourists may already have done enough to record a second successive series victory over South Africa in this format.
Anderson (five for 23), making light of a knee niggle which required significant strapping to his right leg, was the irresistible force as England ushered their hosts out for only 119 in 37 overs.
Then the reliable Jonathan Trott bagged an unbeaten 52 to complete the job with minimum fuss and more than 18 overs to spare.
Smith lasted only four balls first thing - and then watched his team falter terminally, only Alviro Petersen (51) putting up worthwhile resistance on a pitch of evident easy pace and even bounce.
Both Stuart Broad and Anderson found enough swing to test the batsmen from the outset. Smith went in the second over with only six on the board, to Broad's second legitimate ball.
England's new-ball pair had each begun their day with a wide. But Broad then got some full-length swing on target, and Smith missed to be lbw to one that pitched just in line with leg-stump.
Hashim Amla struck South Africa's first boundary - a back-foot drive past extra-cover off Broad from the last ball of the fourth over.
But when he tried to repeat the dose through midwicket off Anderson, he found the man in the ring at easily catchable height.
AB de Villiers, the scourge of England with a breathtaking hundred at Newlands two days ago, was joined by JP Duminy.
There appeared little margin for error with short balls. But England profited when Duminy was early on a pull at Anderson and somehow looped a simple catch behind to Matt Prior.
Perhaps the biggest wicket was De Villiers', shuffling across and missing a turn to leg in Tim Bresnan's first over. On another day, he might have been spared the lbw verdict.
Petersen had, however, announced himself with a pull and off-drive for successive fours in Luke Wright's first over - and it seemed there could still be a decent total on a perfectly feasible surface.
But that was not to be, Anderson returning at the Duckpond end to take two more wickets with the score stuck on 78.
The first significant sideways movement off the pitch did for Mark Boucher, Anderson clipping the top of off-stump with a very good delivery which held its line.
As England piled on the pressure, Ryan McLaren's attempt at a relieving shot merely saw him squirt a drive straight to backward point to go for a duck - and even with Petersen still there, South Africa's hole was getting deeper and deeper.
Anderson was not done yet, and a little extra effort in his final over was enough to have Johan Botha fencing a catch behind to give the Lancastrian his career-best figures in his 120th ODI.
Paul Collingwood nipped in for two wickets too - the first his 100th at this level - and although Petersen's 73-ball 50 kept England waiting, he was last out to an athletic catch at mid-on by Wright off Broad as South Africa registered their lowest ever ODI score on home soil.
England's successful reply appeared little more than a formality, especially with the early cloud almost entirely dispersed.
Andrew Strauss and Trott put 31 on the board in seamless fashion in half an hour before lunch.
The captain eventually went lbw after a stand of 74, trying to cut a Botha arm ball - ensuring a Kevin Pietersen innings, and resulting interaction for an otherwise largely redundant crowd.
They booed loudly as their favourite anti-hero made his way to the crease, were speechless when he was badly dropped on nought by Morkel second ball - mis-hooking McLaren to long-leg - and whistled him on his way for a manic three after he chipped Botha compliantly to midwicket.
A third wicket fell for only nine runs when Collingwood drove and edged behind at some McLaren swing. But the wobble had come too late to seriously worry England.