South Africa continue to be plagued by injury problems ahead of their three home matches in the Tri-Nations series.
Andre Pretorius broke down during a tough training session
Fly-half Andre Pretorius, who did not tour Australia and New Zealand due to a groin injury, had to stop training on Monday because of shin splints.
And lock Danie Rossouw was also forced to sit out the entire session.
"Both those players will undergo MRI scans on Tuesday and then we will know how to manage their injuries," said Springbok coach Jake White.
"At least I had 26 of the 28-man squad training properly, but the players are still not where I want them to be conditioning-wise."
Of course it will be a challenge, because we have a couple of injuries and we can't put our ideal team out on the field
South Africa were thrashed 49-0 by Australia in Brisbane, but improved to lose 35-17 to the All Blacks in Wellington and 20-18 to the Wallabies in Sydney.
White believes his team can win their home fixtures.
"You've got to be confident. The reality is we have a very proud record at home and we've beaten both New Zealand and Australia here in the last year," he said.
"Of course it will be a challenge, because we have a couple of injuries and we can't put our ideal team out on the field.
"But the players had a very hard session today and dealing with injuries is the nature of what we do in rugby. I'm sure we'll be fine going forward.
New Zealand will play South Africa in Pretoria on 26 August and in Rustenburg on 2 September.
And then Australia arrive for the Tri-nations finale in Johannesburg on 9 September.