Tammy Beaumont's half-century led England to a six-wicket victory (DLS method) over South Africa in a rain-affected encounter which saw the tourists clinch the ODI series 2-1 in Potchefstroom.
Chasing a revised target of 152 runs from 23 overs, England fell to 25-3 after Marizanne Kapp (3-24) took a three-for, losing Maia Bouchier (4), Nat Sciver-Brunt (0) and captain Heather Knight (6) all in single figures.
However, opener Beaumont (65no) and Amy Jones (49no) shared an unbeaten 90-run partnership for the fifth wicket to help the tourists get over the line after a lengthy rain delay, posting 153-4 with four overs to spare.
Earlier, Kate Cross suffered a back spasm during the first over which forced her to the sidelines for the rest of the match, but England still delivered a strong bowling performance, with Sophie Ecclestone (2-26), Alice Capsey (2-59) and Charlie Dean (2-52) all taking two wickets apiece, holding South Africa to 233-8.
Captain Laura Wolvaardt (61) top-scored after being inserted, reaching her 34th half-century - and eighth at the JB Marks Oval - but England made regular breakthroughs to disrupt the middle order and hold South Africa to an under-par total on a batting-friendly wicket.
England will now face South Africa in a one-off Test in Bloemfontein, starting on Sunday, live on Sky Sports Cricket, to conclude the all-format series.
England lost Bouchier and Sciver-Brunt in the opening over to Kapp after the former picked out Nadine de Klerk at short mid-wicket and the latter found Anneke Bosch at point, leaving the visitors 4-2.
Skipper Knight was then bowled by Kapp whilst Danni Wyatt-Hodge added a necessary 22 to England’s tally before she was trapped lbw by Chloe Tryon (1-26).
Jones passed 2,000 ODI runs during her late cameo with Beaumont as the pair dragged England from 63-4 to a match- and series-winning 153-4, sharing 16 boundaries between them.
Lara Goodall (17) shared a 50-run opening stand with her captain before she was dismissed by Lauren Bell after clubbing to Beaumont at mid-on in the 10th over.
The second wicket fell twelve overs later after Bosch (19) tamely lobbed an arm ball from Capsey to Knight at short cover.
Wolvaardt brought up a 60-ball half-century with a crisp cover drive for four which brought stability into South Africa’s innings, taking the hosts to 107-2 before she was trapped leg-before by Ecclestone.
De Klerk (14) was run out by Bouchier after being caught well short of her crease despite a full-stretch dive before Charlie Dean dismissed Annerie Dercksen (13) lbw to leave the hosts 156-5.
Kapp looked in good form as she hit four boundaries in her 54-ball outing but holed Capsey out to long-on as Mieke de Ridder (19no) took South Africa past 200
Tryon ambitiously galloped down the pitch looking to hit Ecclestone and missed, leading to her being stumped by Jones.
Dean then struck again to remove Masabata Klaas for a duck after she ballooned a wide delivery straight to Sciver-Brunt at mid-off.
De Ridder and Nonkululeko Mlaba (16no) stood firm though, sharing an unbeaten partnership worth 32 runs to defy a lower-order collapse and guide the hosts to 233-8.
England captain Heather Knight:
"I think it's a brilliant effort after losing your opening bowler in the first over [Kate Cross suffering a back spasm] and to rally round on a flat wicket in the heat. It's really outstanding.
"The fact we kept taking wickets really helped us, we had a brilliant last 10 overs and taking wickets going into that was key.
"Tammy [Beaumont] set the tone really early, was really smart with the ends she picked to attack, and to be under pressure in a must-win game, I think that partnership at the end was brilliant."
South Africa captain Laura Wolvaardt:
"I think we started well with the bat but probably just came up a bit short - lost a few too many wickets in clusters like the other day and couldn't make the most of the last 10 overs.
"The selectors have the future in mind with the next 50-over World Cup being next year, so they're trying to see all possible combinations and I guess that's what they thought was right on the day."
All times UK and Ireland; all games live on Sky Sports
