Graeme Smith said he was surprised with Australia's decision to bowl first in the fourth one-day international in Port Elizabeth.

Opposite number Ricky Ponting won the toss and asked the hosts to bat on a flat St George's Park track, and then watched as Herschelle Gibbs slammed a century to help his side post 317 for six.

AB de Villiers also played a key role with 84, before Dale Steyn snared four wickets as the tourists - despite fifties from Brad Haddin, Michael Clarke and Ponting himself - were dismissed for 256.

"It is a bit unusual for Australia to bowl first in big games," said Smith afterwards. "But once we posted 317, we were always confident.

"At 129 for nought, we were a little bit nervous, but the boys did really well and showed a lot of character. It was another very good day for us."

Superb job

The win allowed South Africa to take an unassailable 3-1 lead in the five-match series and Smith was full of praise for his charges.

"Obviously we wanted to play well and win the series here," he said. "I think the batters did a superb job.

"Again in our top four we got one really big partnership and it was nice to have someone to go on and get a hundred as Herschelle did.

"He's been getting a few starts, so it's nice that he cashed in. So it was a good day."

Good energy

The Proteas skipper is now looking to end their battle against Australia with another win on Friday, adding: "I think there's some really exciting players coming through.

"Everyone's contributing with bat and ball - there's a really good energy in the squad.

"We just need to keep our feet on the ground and take one step at a time. So we'll look to finish the series on a high note at the Wanderers and if we do make it 4-1, then it will really make a top-standard series for us."

Australia captain Ponting refused to blame his decision earlier in the day for their loss.

"There was enough there this morning and I think we even capitalised on it early on," he said. "Herschelle obviously played beautifully today, I think he played a sensational innings.

"I thought De Villiers was also outstanding.

"We needed someone at the top to go on and make a big hundred, but we didn't really have that.

"As I said, I thought there was enough movement in the air and the wicket was just slowing and holding up enough to do some damage early on, but we didn't capitalise on it. So full credit to their batsmen for the way they played today."

Ponting has now called for a reaction from his players in the fifth match at the Wanderers.

He added: "We weren't able to do well this time, and the South Africans outplayed us in the last three games in all facets of the game, so they deserve to be where they are.

"We'd like to finish the tour on a high, so hopefully there'll be a bit of character in the team when the guys pitch up on Friday."