Slowly does it for Siddle

Peter Siddle believes South Africa's ultra-defensive batting approach could play into Australia's hands in Adelaide.

The hosts moved towards victory on day four of the second Test in Adelaide.

Chasing an unlikely victory target of 430, the tourists curbed their attacking instincts early, crawling to 77 for four from 50 overs and scoring just 42 off their last 43 overs.

Faf du Plessis and AB de Villiers were the not out batsmen after combining for a snail-paced unbroken partnership of 32 in 29 overs.

"It's going to be hard, but that (the slow scoring rate) plays in your (Australia's) favour as well," said Siddle, who turned 28 on Sunday.

"I think being defensive leaves you open to get those nicks and to play to the fielders where we're placing them. It can work both ways."

As frustrating as the partnership between Du Plessis and De Villiers was for the home side - and the spectators - Siddle claimed the hosts are were still firmly in the box seat.

"It's going to be hard work, but I think all in all it's a pretty good end to the day," the paceman said. "We're in a good position, but there's obviously still a lot of work tomorrow morning to be done.

"If we stick to the same stuff we did this afternoon, we can finish on a good note.

"We'll keep pushing for those six wickets tomorrow morning."

Australia will look to make further inroads early on, knowing they have just three specialist bowlers at their disposal with pace spearhead James Pattinson sidelined and out of the remaining four Tests of the summer with a rib injury.

"It is disappointing," Siddle said of Pattinson's latest injury. "I think everyone knows he's going to be down and not going to be a happy chap at the moment.

"He's still confident. He's just disappointed he can't get out there now and back us up and have a crack.

"It's a disappointing time for him but he'll come back strong."

In Pattinson's absence, the onus will be firmly placed on Siddle and Ben Hilfenhaus to bowl well, alongside off-spinner Nathan Lyon, who took two wickets for 15 runs today.

"Monday morning we've just got to be as fresh as we can be, especially Hilfy and myself," Siddle said.

"Hopefully (we can) get a bit of reverse swing going.

"We know we've got the second new ball as well and an opportunity to have a crack at them with that.

"We've still got a couple of options up our sleeve.

"Nath is going to play a big role at that other end and hopefully get a few balls out of the rough and keep working them over.

"He is going to have to hold up that end for the rest of this innings and the quicks from the other end.

"If we can keep building the pressure and keep working away I think the six wickets will come around."

South Africa assistant coach Russell Domingo admitted a draw was now the best South Africa could hope for.

"Definitely," Domingo said. "We know that 353 on the last day with four wickets down is probably out of the window. We South Africans pride ourselves on our resilience and we'll fight right through to the end.

"We know we're under a bit of pressure at the moment. There's every possibility that something special could happen and there's an opportunity for someone to make a major play for his country."