England handed one-day international debuts to Somerset batsman Tom Banton and Lancashire leg-spinner Matt Parkinson in the series opener against South Africa at Cape Town.
The tourists – in their first ODI since winning the World Cup last year – retained only captain Eoin Morgan, plus Jonny Bairstow, Jason Roy, Joe Root and Chris Woakes from the side which defeated New Zealand in last year's final.
Morgan lost the toss under glorious blue skies at Newlands, where England were invited to bat first by South Africa's newly appointed ODI skipper Quinton De Kock. The Proteas handed ODI debuts to JJ Smuts and Lutho Sipamla.
The world champions have not lost an ODI bilateral series since the start of 2017, when India edged them out. Since then, England have won 12 of their 13 series, the only blemish a 2-2 draw against the West Indies last year.
However, South Africa prevailed in the corresponding series four years ago, overturning a 2-0 deficit to win the final three ODIs.