A scan revealed a back injury to Du Plessis, ruling him out for six to eight weeks, while Geduld underwent an operation on Tuesday to remove cartilage in his knee. He will also not play for at least six weeks.
The return to play for Springbok Sevens captain, Philip Snyman, has not been confirmed.
“Philip has been reviewed by a specialist and the scans showed that his injury involves the sternocostal joint (between the breastbone and the first rib)," said the Springbok Sevens team doctor, Dr Leigh Gordon.
“It is an unusual injury. We will have to see how his rehabilitation goes in January before we can make a call. Obviously, we hope that he will be available for selection for the tournaments in Hamilton and Sydney, a week later.”
Werner Kok, who underwent surgery for facial fractures on Monday, will be fit to return to training early next year, Gordon said.
"Werner’s surgery went well and he will join the squad in January. He may miss the first few days of contact but is expected to be available for selection,” said Gordon.
A number of players who missed the first two tournaments of the season due to injury will be available for the Australasian leg, including the Blitzboks’ top points' scorer of all time, Cecil Afrika, as well as Stedman Gans and Heino Bezuidenhout.