The Tri-Nations rivals meet in Sunday's World Cup quarter-final at Wellington Regional Stadium, with the Wallabies starting as marginal favourites.
Defending world champions South Africa possess a team that many believe will never recover former glories, with players such as John Smit and Victor Matfield in the autumn of their careers.
But second-row enforcer Botha has demanded that any thoughts of retirement are delayed for another week by toppling Australia.
"A handful of us have been around the block for nine, 10 years and the big secret for us is to focus on the weekend," he said.
"When you pull that green and gold jersey on you must give it your all and we are not holding back one inch.
"We know from this weekend the intensity is going to get higher and the pressure as well.
"A lot of the guys know it can be their last game and the team that loses this weekend is on their way home, so we know what we must produce."
Botha believes Tri-Nations champions Australia have developed their forward play over the last two years.
"Since Robbie Deans took over the Australia pack have picked up their physicality a lot, as we saw in the Tri Nations," he said.
"They are a much more physical side than three or four years ago.
"You can't play Test rugby if you have not got a pack that dominates physically and this weekend's battle will be physical.
"We must get on the pitch, do our best and have a good day at the office.
"Every Test is a clash of the packs, where we make a few deals and everything in the rucks, sorting each other out.
"We know that a Test match against Australia is a physical battle and that's the first battle we must win to put our backline on the front foot."
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