South Africa captain Faf Du Plessis hailed David Miller for his "incredible" and "ridiculous" innings in their win over Australia.

Miller struck an unbeaten 118 off 79 balls as the hosts chased down a record 372 in Kingsmead, Durban on Wednesday.

Centuries from David Warner and Steve Smith had put Australia in a strong position, but Miller smashed 10 fours and six sixes in an incredible chase, seeing South Africa to a four-wicket win with four balls to spare.

"I thought 320 on this deck would've been par," Du Plessis said.

"We took the confidence that the deck was pretty good and that we needed to stay ahead of the rate at all times, which we did really well. That's one thing we did really well, right through the innings we were ahead of the rate.

"But still in that we made a few errors and I thought we could've made the job a lot easier and not left the incredible, ridiculous innings like that from Dave.

"To win a game like that when you're supposed to lose, and down and out, and you have someone put their hand up and take you across the line, it's as good as it gets.

"For me it was nice to see someone in the middle get through and get 100."

Opener Quinton De Kock (70) helped set up the win, which gave South Africa a 3-0 lead in the five-match series.

Du Plessis is proud of his side's recent performances and knows they have surprised people.

He said: "There's a lot of people if you asked them, 3-0 South Africa against Australia, number one team in the world, they would've possibly laughed.

"It just shows which direction we're going in as a team at the moment.

"We've played some really good cricket in all formats the last while and I'm really excited for what lies ahead."