Ruan Combrinck is expected to miss the remainder of the Rugby Championship after sustaining a fractured fibula in South Africa's 26-24 loss to Argentina in Salta on Saturday.
Springboks wing Combrinck was replaced by Jesse Kriel seven minutes before half-time and was taken to hospital for X-rays.
The assessment revealed a fracture that will keep the 26-year-old out of action for the next six weeks, likely ruling him out of contention for forthcoming Tests against Australia and New Zealand.
The Springboks have already lost Julian Redelinghuys to a hamstring problem and their injury troubles could increase with fly-half Elton Jantjies set to undergo a scan on a groin issue sustained in the second half.
Jantjies' replacement Morne Steyn put South Africa ahead by a point with six minutes remaining, but a last-gasp penalty from Santiago Gonzalez Iglesias clinched the win for the Pumas.
Springboks coach Allister Coetzee did not begrudge the hosts the victory, ruing individual errors from his team.
"I want to congratulate Argentina for their win. As a team, we made some crucial mistakes and they made better use of their opportunities than we did," said Coetzee.
"Although we lost Ruan and Elton because of injuries, we managed to come back in the second half. However, I am disappointed by the many individual mistakes that we committed.
"We had enough opportunities to create scoreboard pressure, but we did not take them. At Test level, you must take your opportunities or you will get punished. We missed some penalties and also didn't score tries when we were in a position to do so.
"Credit to Argentina because they really worked for their victory. The defeat is hurting and the Springboks will never be satisfied with a loss.
"We will regroup and work hard to improve as a team so that we can be ready for the next Test against Australia in Brisbane."
SANZAR confirmed after the match Springboks flanker Teboho Mohoje was issued with a citing commissioner warning, which will count as a yellow card on the players' record for the tournament, for a dangerous tackle.