Alex Hales' century provided the only substance for England as they were bowled out for 236 in their one-day international decider against South Africa at Newlands.
Hales (112) capped his hugely consistent series by turning his fifth successive half-century into his only hundred, the second of his ODI career.
But there was precious little support as no one else reached even 30 and the tourists lost their last seven wickets for 81 to last only 45 overs, and put themselves in danger of losing 3-2 in a series they led 2-0 at the start of this week.
Hales became only the fifth Englishman to hit five consecutive ODI 50s and the first to do so in the same series. His hundred came up off 116 balls and contained 13 fours.
There were occasional false shots from him, and necessary but hardly outrageous fortune, with movement for all bowlers after AB de Villiers won the toss.
At the other end England were largely hapless as Kagiso Rabada, David Wiese and Imran Tahir took three wickets each.
A frenetic first 10 overs went England's way as Hales and Joe Root passed 50 together for the fourth time in as many matches.
Hales' opening partner Jason Roy was pinned lbw on the back foot by a leg break after De Villiers surprisingly introduced Tahir for only the fifth over.
South Africa then immediately returned to seam at both ends, with a plan for Root.
Chris Morris attacked England's linchpin number three on the back foot, with leg-side catchers in abundance - and when the full ball came Root edged to slip on 12 only for Hashim Amla to put down a straightforward catch.
It was not costly - because Tahir returned and, overturning an initial not-out verdict from Johan Cloete, had his second lbw victim when Root missed a sweep at a straight one.
Eoin Morgan tried to kickstart his innings with a big shot, but managed only an outside edge behind on the charge at Wiese - for his third successive single-figure score.
Ben Stokes helped Hales put on 70 as England reached the promise of 155 for three in the 28th over.
But Rabada returned, and changed the match with two big wickets in as many legitimate balls.
Stokes wandered too far across his crease in search of a leg-side flick and was bowled, then Jos Buttler took his sequence to one run in three innings since his heroics in the first two matches.
He watched a wide go by first ball, but then fell to his second when Rabada snaked a very good delivery through forward-defensive bat and pad to hit leg stump again.
A desultory procession followed as Hales' potential came and went all too briefly.
He retained his composure to reach three figures with an emphatic on-driven boundary off Morris but even he eventually succumbed, pulling Rabada to the square-leg boundary before Stuart Broad was last out to Tahir.