England's 59-run win in the third and final ODI put a massive dent in South Africa's hopes of qualifying directly for this year's ICC Mens Cricket World Cup.
Skipper Jos Buttler (131 off 127 balls) and Dawid Malan (118 off 114 balls) shared a 232-run partnership for the fourth wicket after the hosts had reduced England to 3/14 in the sixth over.
That helped the visitors put up a massive 346/7 in their 50 overs. Archer collected his best ODI bowling figures of 6-40 in just his second international appearance back from a long injury break as South Africa were bowled out for 287 in 43.1 overs.
While South Africa claimed the three-game series 2-1 after winning the first two games, the loss in the final match left them precariously placed as teams jostle for the eight automatic qualification spots for this year's 50-over World Cup in India in October-November this year.
South Africa currently sit in ninth place on the ICC Cricket World Cup Super League standings with a total of 79 points and now have a nervous wait on their hands to see if they qualify automatically, said a report on the ICC's official website.
The upcoming series between New Zealand and Sri Lanka will be pivotal to the final standings, while the Proteas still have two further matches up their sleeve - against the Netherlands at home at the end of March - that could still revive their chances.
While the top eight teams on the Super League standings qualify directly for the 50-over World Cup, the remaining sides can still progress via the ICC Men's Cricket World Cup Qualifier that is scheduled to be held in Zimbabwe in the middle of the year.
The five remaining teams plus five Associate teams will battle it out for the final two spots at the World Cup and the likes of South Africa, West Indies and Sri Lanka may have to take this route should they not be able to sneak into the top eight places on the Super League standings.