Siya Kolisi's troublesome ankle could force Springbok coach Allister Coetzee into making radical changes in the back row for Saturday's Rugby Championship opener against Argentina at the Nelson Mandela Bay Stadium in Port Elizabeth.
Tightead prop Frans Malherbe has already been ruled out of Saturday's match with a neck injury, and star flank Kolisi could join him on the sidelines. Kolisi initially took part in the team's training session at the match venue on Monday afternoon, but was withdrawn halfway through the session and sat in the dugout nursing what looked like his ankle.
The Stormers flank sustained an ankle injury during the Super Rugby semifinal against the Chiefs last month, and was still walking around with a moon boot about two weeks ago.
The Boks are already without their captain and No 8 Warren Whiteley, who missed the last June Test against France and the latter part of the Lions' Super Rugby campaign due to injury.
"Warren underwent surgery on Friday and they found a tear in his abdominal muscle, and that was repaired. He will now continue with his physiotherapy and rehab," Springbok team doctor Konrad von Hagen told reporters on Monday.
Cheetahs loose forward Uzair Cassiem looks likely to start at No 8 in the absence of Whiteley, while Lions flanker Jaco Kriel and Cheetahs hardman Oupa Mohoje are the favourites to pack down on the sides of the scrum. Sharks bulldozer Jean-Luc du Preez, who started at No 8 in the third Test against France, may come off the bench.
The reason why the young Du Preez could be overlooked for a starting berth in Saturday's match is because of the way the Bok lineout struggled against the French when Mohoje and Whiteley were not available for the Ellis Park match.
Du Preez is a physical beast, who made a massive impact for the Boks in that second Test in Durban, climbing in with big tackles and telling carries, although he struggled in the lineouts at Ellis Park. The Boks' attack just couldn't get going in that match, because they were unable to secure ball at the back of the lineout.
Cassiem was the Boks' best player on the park in a losing cause in his first and only Test against Wales in November. He carried well in that match, while his work-rate was also good.
"Warren's injury is a big blow to our team. What he did in the wide channels, his work-rate, his leadership abilities, his lineout abilities ... that's not something you change in a day," Springbok assistant coach Johann van Graan told the media on Monday.
"With that being said, I've been very impressed with Uzair Cassiem. He's worked very hard on his lineout detail. And during Super Rugby he played six, seven and eight for the Cheetahs, so he can cover one or two of those areas.
"I'm very confident in our loose forwards' ability and to execute the plan."
There is also a likely start for Coenie Oosthuizen at tighthead against Los Pumas after Frans Malherbe, who started in two Tests against France, was ruled out of the tournament with a neck injury. Malherbe is replaced in the squad by Ruan Dreyer, the Lions prop who made his Springbok debut in the third Test against France.
Malherbe underwent scans on Monday afternoon in Port Elizabeth to determine the severity of the injury after complaining about stiffness in his neck.
"Frans consulted a neurosurgeon who suggested extended rest for the player, with follow-up scans to be done in two weeks' time," added Von Hagen.
Scrumhalf Ross Cronjé and Handré Pollard are the other two injury concerns in the group. Both trained on Monday, but Cronje didn't take any contact after a shoulder injury sustained in the Super Rugby final for the Lions against the Crusaders.
"Ross Cronjé didn't train last week due to a sternoclavicular joint [niggkle] and first-rib joint that he sustained in the [Super Rugby] final. We will see if he can take contact during the latter part of the week and then we'll make a decision on his availability," Von Hagen continued.
"Handré Pollard took part in full training sessions on Thursday and Friday, and we'll continue to let him training with the squad and that way work on his fitness and complete his final phase of rehabilitation."