Palu was selected by coach John Connolly in one of two changes from last weekend's 13-9 loss to New Zealand.
Palu replaces Scott Fava at number eight while hooker Tai McIsaac comes in for Jeremy Paul.
Paul drops to the bench while Fava has been left out of the party.
"There are a couple of positions we haven't settled on and the back row is an area we are looking very closely at," Connolly said.
"(Palu) is a huge man and he gives us another strong ball-carrying option.
"He's still developing a number of aspects of his game but has a lot of potential. He's an important part of our philosophy of expanding our base in the lead-up to the World Cup."
Connolly admitted facing the Springboks was a tough test for his side after such a gruelling loss to the All Blacks.
He added: "The match against New Zealand took a lot out of the players both physically and mentally, so it's a big challenge for them to get up for a test against South Africa with such a short turnaround."
South Africa named Johann Muller at lock ahead of Albert van den Bergh in the only forward change to their starting line-up from the 35-17 loss to New Zealand in Wellington two weeks ago.
Winger Akona Ndungane returns from injury in place of Breyton Paulse.