Despite their first defeat of the competition, South Africa next face West Indies at Wellington, knowing that one more victory will secure their place alongside Australia in the semi-finals
Wellington: South Africa 271-5, Australia 272-5 - Australia win by five wickets
Meg Lanning hit a fine hundred as Australia retained their unbeaten record at the Women's World Cup by beating South Africa in an excellent game between the tournament's top two sides.
Lanning ended unbeaten on 135 as her side chased down their 272-run target against the Proteas, who had earlier reached a seemingly competitive total thanks to 90 from Laura Wolvaardt.
But Australia's strength in depth meant that Ellyse Perry, who spent time off the field with a sore back, was not required to bat, with Beth Mooney, Tahlia McGrath, Ashleigh Gardner and Annabel Sutherland all supporting their captain through valuable cameos during the middle overs of their run-chase.
Lanning's century was her 15th in ODIs, with Australia – who had already qualified for the semi-finals – securing their sixth straight win with 28 balls remaining. They will make it a clean sweep of the round-robin phase if they beat Bangladesh in their final group game.
Earlier, South Africa's opening pair of Wolvaardt and Lizelle Lee had put together the first powerplay partnership of note against the tournament favourites, adding 88 at the top of the order before Lee fell for 36.
Ashleigh Gardner took a stunning catch on the boundary to dismiss Mignon du Preez (Mark Tantrum/Getty Images)
Lara Goodall followed soon afterwards, but captain Sune Luus made a run-a-ball fifty, before cameos from Mignon du Preez, who was brilliantly caught in one hand by Gardner at deep midwicket, Marizanne Kapp and Chloe Tryon ensured a strong finish after being asked to bat first.
In reply, Alyssa Healy departed early to Shabnim Ismail – one of two wickets for the speedster – and Rachael Haynes followed in the first over outside the powerplay, but Lanning then took control.
Despite their first defeat of the competition, South Africa next face West Indies at Wellington, knowing that one more victory will secure their place alongside Australia in the semi-finals.