Australia's physically vulnerable pace attack say they won't risk breaking down and leaving teammates a fast bowler short on the WACA wicket in the decisive third Test.
Spearhead Peter Siddle said he was confident of recovering in time from his marathon effort in Adelaide but promised he would do the right thing and fess up to captain Michael Clarke if he's not right to go by Friday.
The No.1 Test ranking is up for grabs and Siddle said there will be nowhere to hide against the South Africans.
Australia can ill-afford a repeat of the second Test draw, where James Pattinson was forced out with injury and the attack was left stranded in blazing hot conditions on the final day.
"Obviously I don't want to miss any Test matches ... but I've still got to think of the end result," said Siddle, who expects a final say on his fitness and doesn't anticipate selectors enforcing the rotation policy on him without consultation.
"I'm feeling good now, I've recovered well ... but if I'm struggling through tomorrow or if I don't feel 100 per cent I've got to talk to the captain, the selectors and work out what's best.
"You see the hard work... (Ben Hilfenhaus) and myself had to go through.
"You don't want that happening again here where it's such a big game and so much riding on the line."
Australia played four quicks in last summer's thrashing of India in Perth, and the option is there again with Mitchell Starc, Mitchell Johnson, John Hastings and Josh Hazlewood all picked in the squad.
However given spinner Nathan Lyon's more settled position in the team and the fact Shane Watson can bowl, three front-line seamers seems more likely.
If Siddle and Hilfenhaus do play, more pressure will rest on Watson's shoulders in his return from a calf problem.
But the injury-prone vice-captain said he wouldn't have been picked as an allrounder unless he felt he was capable of bowling as many overs as could potentially be asked of him by Clarke.
"I understand (bowling a lot of overs) could be a possibility for me ... but in the end my body is in the condition to do it," Watson said.
"I'm certainly fresh compared to some of the other guys who have been out there, so my body should be right.
"Over the last week I've been gradually building up my running and my bowling.
"The selectors will no doubt keep in mind the best way to get the 20 wickets over this next Test match."
Young left-armer Mitchell Starc is favoured to play given he's been 12th man from the past two Tests and Pattinson has now vacated a position.
Starc took four wickets against India in Perth last year but said he's still in the dark over selection.
"My approach hasn't changed as opposed to the first two Tests. I just try to make good contest between bat and ball in the nets and do everything I can to get myself ready to play," Starc said.
"Hopefully I get chance to come out here again and bowl similar to what I did last time."