England needed fewer than ten overs to knock off South Africa's total at the Women's World Cup to keep alive their hopes of retaining the title.
Anya Shrubsole starred for the defending champions by taking 5-17 to help bowl South Africa out for just 77.
England reached their target with more than 40 overs to spare, with Arran Brindle (28*) and Lydia Greenway (25*) putting on an unbeaten partnership of 55 for the fourth wicket.
The win was even more special for Greenway who won her 100th cap and passed the 2,000 run mark in one-day internationals.
Player of the match Shrubsole told ECB.co.uk:
"The batters backed us up brilliantly. Losing those few wickets was irrelevant; we just needed to knock those runs off quickly and the batters did that."
Despite the win, England still aren't sure whether they'll qualify for for the semi-finals.
Super Six rivals New Zealand and West Indies, who are both above England on net run rate, sqaure off on Monday.
If the Windies win then England will need Australia to beat the Caribbean side in their final group game.
Should New Zealand be successful then England will need to beat them on Wednesday and get their net run rate above the White Ferns.