Five-time champions Australia battled through to Sunday's final of the 50-over World Cup against India with a nervy three-wicket win against South Africa in the second semi-final on Thursday.

Australia captain Pat Cummins talked about the couple of nerve-wracking hours during an intense semi-final but while Australia rejoiced in making another World Cup final, South Africa faced yet another heartbreak. 

"Nerve-wracking couple of hours but great effort and a great game," said Cummins, who was especially pleased with his side's fielding. "It's something we talk a lot about. It wasn't up to scratch at the start of the tournament."

"Easier than sitting in the dugout," Cummins had said about being out in the middle during an intense chase.

The chase has not been South Africa's forte in the tournament and Temba Bavuma's decision to bat first under an overcast sky seemed to be a no-brainer.

Bavuma played the match despite not having fully recovered from a hamstring strain and his four-ball duck suggested sitting out would probably have been a wiser decision for him. David Miller's ton however gave the Proteas plenty of ammunition to defend their score of 212.

Man-of-the-match Travis Head (62) led their rollicking start before a mid-innings wobble put Australia in a spot of bother as South Africa's spinners injected fresh excitement into the contest.

Keshav Maharaj bowled Head through the gate and Tabraiz Shamsi dismissed Marnus Labuschagne and Glenn Maxwell to jolt Australia out of any complacency that might have crept in.

Steve Smith made 30 and Josh Inglis scored 28 but South Africa kept fighting back. However, Cummins and Starc combined to foil the Proteas and get Australia over the line.

"Quite hard to put into words," a dejected Bavuma said. "Our character came through. It was a dog fight.

"The way we started with the bat and the ball was probably the turning point, we lost it quite badly there."