A sloppy Australia dropped five catches, which put them on the backfoot as South Africa posted 311-7 thanks to more brilliance from De Kock (109), who scored his second century in as many matches.

Australia could only muster 177 in reply and are one of four teams still without a win - Sri Lanka, the Netherlands and Afghanistan being the others - after they lost their opening game to tournament hosts India by six wickets at the weekend.

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Australia won the toss and elected to bowl on a relaid pitch but were sloppy on the field, dropping five catches before getting bowled out for 177 - its second below-200 total in the tournament.

De Kock put on 108 with captain Temba Bavuma (35) for the opening wicket, and was well supported by Rassie van der Dussen (26) and Aiden Markram before falling for 109 in the 35th over, having faced 106 balls and struck eight fours and five sixes.

That did not halt the Proteas' momentum, with Markram making 56 and Heinrich Klaasen, David Miller and Marco Jansen all chipping in with valuable runs to take them past 300.

Fast bowler Kagiso Rabada picked up 3-33 and Keshav Maharaj clamped the batters by chipping in 2-30 in a 10-over spell. Only Glenn Maxwell (2-34) showed some spark with his offspin bowling in an otherwise poor day in the field for Australia.

Australia, who dropped several chances, never got going in reply and lost openers Mitchell Marsh and David Warner in successive overs with the score on 27.

They were chasing 312 to win but found themselves five wickets down for 65. A DRS decision left Steve Smith (19) bewildered as the batter thought the ball was missing leg stump.

Another third umpire decision seemed to be wrong when Marcus Stoinis (5) was given out for gloving the ball to South Africa wicketkeeper De Kock, but replays suggested the ball that appeared to flick the glove was off the bat.

The sole partnership of note came between Marnus Labuschagne (46) and Mitchell Starc (27), who put on 69 for the seventh wicket.

By then Australia were playing for run rate and, having suffered a second heavy loss, they need a rapid improvement in their next match against Sri Lanka on Monday.

Cummins: Everyone is hurting

Australia captain, Pat Cummins:

"I thought Quin in particular batted really well - couldn't get a breakthrough. From where they were, we were pretty happy with 312, we thought it was chasable.

"Their bowlers bowled really well. We were well off the mark. If we want to be challenging for this tournament, you have got to find a way in all conditions - that's for the bowlers to try and take wickets and for the batters to try and score runs.

"Not much needs to be said tonight. Everyone is hurting. We will regroup and try and make amends."

Player of the Match, Quinton de Kock:

"It was a great win for the boys. We didn't know how the wicket was going to play and I think we assessed conditions really well. We just played accordingly.

"We knew it was going to be a difficult game. We felt very comfortable with 311. We knew that it does get harder to bat second here at night and it proved that."

What's next?

The Cricket World Cup continues with a clash between New Zealand and Bangladesh on Friday, live on Sky Sports Cricket from 9am (first ball at 9.30am).

Australia face a crucial match against Sri Lanka on Monday, with victory almost certainly a must already, while South Africa take on the Netherlands on Tuesday - both games live on Sky Sports Cricket from 9am (first ball at 9.30am). Full World Cup fixture list and timings can be found here.

Watch every game of the 2023 ICC Men's Cricket World Cup live on Sky Sports. You can stream the tournament on NOW