Australia fast bowlers Mitchell Starc and Josh Hazlewood took two wickets each to rip through South Africa's top order in the second World Cup semi-final on Thursday before rain came to the Proteas' rescue.
READ: Cricket World Cup | Proteas ready for Australia showdown
Left-arm quick Starc sent back skipper Temba Bavuma for a fourth-ball duck in the first over and soon Hazlewood had the in-form Quinton de Kock caught for three.
The new-ball bowlers kept up the attack with the wickets of Aiden Markram (10) and Rassie van der Dussen (six) to reduce South Africa to 24-4 after the Proteas elected to bat under cloudy skies.
Heinrich Klaasen (10) and David Miller (10) had taken the score to 44-4 in the 14th over when rain sent the players off the field at Eden Gardens for around 45 minutes before action resumed.
Bavuma had admitted at the toss that he was "not 100%" fit after injuring his hamstring in the win against Afghanistan.
South Africa are chasing their first ever World Cup final after faltering in four semi-finals including two against Australia in 1999 and 2007.
The script of the ongoing match will look worryingly familiar for South Africa.
In the 2007 semi-final against Australia at Gros Islet, St Lucia, they also won the toss and chose to bat.
However, they lost their top four for 27 including skipper Graeme Smith for two.
The Proteas' innings folded for 149 and they went on to lose the match by seven wickets.
Australian quicks Glenn McGrath and Shaun Tait stood out with seven wickets between them as Australia bowled out their rivals in 43.5 overs.
Their batsmen chased down the target with 111 balls to spare.
Australia went on to capture the title by defeating Sri Lanka in the final.
South Africa have a habit of faltering in knockout games despite playing impressive cricket in the group phase as they won seven of the nine matches in the league stage in India.
In their win against Sri Lanka, they piled up a World Cup record of 428-5.
If the action in Kolkata falls victim to the weather, then there is a reserve day set aside on Friday.
Should no result be possible, South Africa would be declared the winners as they finished higher than Australia in the group phase.
The winners will take on undefeated hosts India, who knocked out New Zealand in the first semi-final, in Sunday's final at Ahmedabad.
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