Travis Head conjured a fine all-round performance as Australia defeated South Africa to enter the World Cup final on Thursday.

Head, who took two wickets when South Africa batted, top scored with 62 as the five-time champions beat the Proteas by 3 wickets in an entertaining match at the majestic Eden Gardens in Kolkata.

The Aussies, gunning a sixth ODI World Cup title, will now square off against hosts India, who are eyeing a third crown in the showpiece event, in Ahmedabad on Sunday.

Earlier, David Miller hit a defiant century to help rescue South Africa to a modest 212.

Australia fast bowler Mitchell Starc returned figures of 3-34 after South Africa had been reduced to 24-4 at one stage before Miller and Henrich Klaasen (47) staged a recovery under gloomy skies at Kolkata's Eden Gardens.

The left-handed Miller reached his ton in 115 deliveries with a six off Pat Cummins but the Australian captain dismissed him two balls later on 101. 

The innings folded soon after in 49.4 overs. Cummins and Starc took three wickets each while fellow quick Josh Hazlewood and part-time spinner Travis Head bagged two apiece.

Left-arm quick Starc struck in the first over to send back South Africa captain Temba Bavuma, who had said he was not "100% fit" at the toss, for a fourth-ball duck. Hazlewood claimed the wicket of in-form Quinton de Kock for three as Cummins took a stunning catch.

The new-ball bowlers kept up the attack with the wickets of Aiden Markram (10) and Rassie van der Dussen (six) as South Africa slumped and were 44-4 when rain interrupted play.

Klaasen and Miller hit back after the 45-minute rain break as the two hit regular boundaries.

The pair put on 95 for the fifth wicket but Head broke through to bowl Klaasen for 47.

Head trapped Marco Jansen lbw on the next delivery to be on a hat-trick, which was saved by Gerald Coetzee.

Coetzee, who has been a breakout star for South Africa with 18 wickets, kept Miller company in a partnership of 53.

Miller smashed eight fours and five sixes in his 116-ball knock.

Coetzee fell caught behind off Cummins but replays suggested the ball grazed his shoulder and not his bat, but the batsman walked off without reviewing.

South Africa were trying to reach their first ever World Cup final after faltering in four semifinals including two against Australia in 1999 and 2007.