On-loan Sharks lock Franco van der Merwe has joined the Springbok training group currently in camp in Durban due to injuries to two locks.
Van der Merwe, who is contracted to the Lions, joined the training squad of 38 players on Monday.
"Both Juandré Kruger and Flip van der Merwe are unable to take part in the field sessions, necessitating the call-up for Franco," said Springbok head coach Heyneke Meyer.
"There are a few players carrying niggles and we will manage them accordingly, but with Juandré and Flip out, we're a bit thin at lock, which is why it was decided to bring in Franco, who has been part of a number of Bok squads since last June.
"Juandré and Flip will remain with us until Tuesday morning, when the training camp concludes, and luckily Franco has been part of the squad before, so he slotted in easily."
The second Bok training camp concludes on Tuesday when the players will return to their franchises for the final round of Super Rugby action before the break for the June Tests.
The final Springbok squad for the Series, involving Italy, Samoa and Scotland, will be named in Cape Town on Saturday.
"We don't have a lot of time to prepare for the first Test, against Italy in Durban next Saturday, so to see the enthusiasm from the players at this camp, is wonderful," said Meyer.
"The work we're doing at these camps will ensure we hit the ground running when we get back together for the Castle Lager Incoming Series on Sunday.
"Italy and Scotland both had very good Six Nations campaigns and will be tough opponents next month, while the Samoans are never to be underestimated. But the players and management are excited about getting together again and doing our best to make South Africa proud of the Springboks."