Looking for some payback after losing 0-57 to New Zealand in Albany three weeks ago, Coetzee will start both Eben Etzebeth and Lood de Jager as locks with Du Toit on the blindside side of the scrum.
The move has caused some criticism in South Africa as a result of Du Toit having been tried in the position before, notably in the loss against Japan at the 2015 Rugby World Cup and last year against England when he had a poor game.
Coetzee said when naming the Springbok side in Cape Town on Thursday: “I can’t comment on the performance against Japan, but yes, against England it maybe didn’t go well on the defensive front.
“But ever since then he has grown and improved a lot. I think you’ll see a much-improved Pieter-Steph on the flank this Saturday.
“He’s made a real conscious effort to be prepared to face a running scrumhalf which presents challenges on defence.
“Being a tall man, he understands what to expect now, and we’ve worked at his body position and ensuring that with the guys around him, he stays within the mini unit,” he said.
Recalled British-based player Francois Louw will play number eight in place of the injured Uzair Cassiem.
Coetzee said the selection was based on securing more ball.
“If you also look at Lood starting, it’s part of ensuring that we have the right options out there.
“We have Franco Mostert providing impact off the bench. Lood is an experienced lineout forward, and with Pieter-Steph there too, you can see that there is quality for our lineout plan.