Lizelle Lee and captain Dane van Niekerk formed the backbone of their side’s 193-3, comfortably overcoming England’s 189-9 with Lee ending unbeaten on 92.
That England had anything to bowl at all was testament to the brilliance of Katherine Brunt. She hit a career-best 72* to help her side recover from 64-6.
Despite Brunt’s heroics it never looked quite like being enough for the hosts - even after taking two early wickets - and they’ll want to come back strongly at Hove and Canterbury.
On a slightly murky morning it wasn’t clear whether batting or bowling upon winning the toss was the right course of action. The coin fell Heather Knight’s way and she opted to bat first.
England started full of intent with Amy Jones in imperious form. The Warwickshire keeper, who’s been in good touch in domestic cricket, struck four sumptuous boundaries before one attempted shot too many saw her chop on for 19.
That bright start soon fell away and with the South African bowlers utilising the nibble in the pitch wickets began to tumble.
Next to go was Sarah Taylor, trapped in front, and captain Heather Knight followed in the same way – struck on the back pad by one that nipped in.
Tammy Beaumont and Nat Sciver rebuilt briefly before the former was bowled by Ayabonga Khaka.
Sciver and Dani Wyatt then tried to stop the flow of wickets but they both departed in close succession, Sciver getting a leading edge to be caught at mid-wicket and Wyatt driving straight to cover.
That brought Brunt to the crease and slowly and surely England got themselves back in to a competitive position.
Brunt was the mainstay; initially watchful, she had Jenny Gunn, Anya Shrubsole, Laura Marsh and Sophie Ecclestone for company and together they eked out 125 runs for the last three wickets.
The Yorkshire all-rounder paced her counter-attack perfectly, adding 50 in 10 overs with the very impressive Laura Marsh before 41 more came quickly alongside Ecclestone. Her partnership with Ecclestone equalled England’s record for the tenth wicket in ODIs.
It gave England something to bowl at and they were quick out of the blocks. The first beneficiary was Brunt – as vivacious and full of energy as she was on debut 14 years ago.
She bowled Laura Wolvaardt before Sarah Taylor pulled off another astonishing Sarah Taylor stumping, the latest in a long line of Sarah Taylor keeping masterclasses.
That gave England hope but Lee and van Niekerk combined for 113 to all but make the game South Africa’s.
Van Niekerk fell to Shrubsole – and Lee almost went the same way until replays suggested Brunt’s attempted catch at long-off had probably made contact with the ground – but South Africa got over the line to go 1-0 up in the series.