Sarah Taylor's third successive Twenty20 half-century eased England's women to a series-clinching four-wicket victory over South Africa at the Wanderers.
Taylor (60) and Heather Knight shared a third-wicket stand of 62 as the tourists chased 131 for four with 27 balls to spare for a 2-1 success.
South Africa did well to push England that far, after recovering from six for three - with Anya Shrubsole on a hat-trick - thanks to a fourth-wicket partnership of 89 between Lizelle Lee (69no) and Mignon du Preez.
Taylor reached her 15th Twenty20 half-century from 33 balls, having hit nine fours - and then for good measure passed 2,000 runs in this format, after Knight was caught-behind from a mis-sweep at Sune Luus.
Dane van Niekerk pulled off a fine caught-and-bowled to dismiss Taylor.
By then, though, England needed only 16 in almost seven overs - and despite a late wobble to the returning Shabnim Ismail (three for 27), Tammy Beaumont finished the job.
The tourists' loss of three late wickets in eight balls was a mere blip, compared with South Africa's early troubles after they were put in.
Tash Farrant, and Shrubsole with her two wickets in two balls, consigned the hosts to a miserable start - before Lee took over with her career-best batting, in a stand which saw captain Du Preez pass 1,000 Twenty20 runs.
Farrant, and England, were indebted to a very good stumping by Taylor off a leg-side wide to see off Trisha Chetty for a duck to the third ball of the match.
Van Niekerk then could not deal with Shrubsole's inswing, and neither could Marizanne Kapp - both bowled in successive deliveries.
South Africa's openers, who had hit 169 runs between them in the first two matches, were gone for an aggregate five this time.
But Lee and Du Preez did the business instead for South Africa.
Lee had an escape on 30, dropped at long-off by Knight in Jenny Gunn's first over - which cost 15.
Knight made minor amends when she responded to a fumble in the deep with a direct-hit flat throw to run out De Preez.
Chloe Tryone then joined Lee, and both hit well - but it was a target which did not seriously extend England.