Full-back Zane Kirchner and hooker Chiliboy Ralepelle did not feature in the two opening wins over Argentina but will travel to Australasia to complete a 28-man squad.
Ralepelle has been suffering from a back injury and will have to pass a fitness test before the squad fly Down Under on Saturday.
"This will be two tough weeks on the road against two of the best sides in the world and as we saw last weekend against Argentina, we still have a lot of hard work to do," Springboks coach Heyneke Meyer told www.sarugby.net.
"The Springboks have never beaten Australia at Suncorp Stadium in Brisbane and our last victory at Eden Park was in 1937.
"We get together on Thursday and will have to put in a lot of hard work in the next 10 days."
South Africa take on Australia on September 7 before facing the All Blacks a week later.