Former Springbok Naka Drotske is in intensive care following a setback in his recovery after being shot in a robbery.
Drotske, a Rugby World Cup winner in 1995, appeared to be recuperating well after the attack in Pretoria.
But a hospital spokeswoman told BBC Sport the 47-year-old was "in a critical but stable condition".
She added: "It is anticipated that he will be ventilated for another couple of days and kept under sedation."
Drotske was pictured giving a thumbs up from his hospital bed in the aftermath of the attack, while his cousin had said he could soon return home.
However, his sister-in-law posted a message on social media saying Drotske had had a setback.
Hospital spokeswoman Barbara Steenkamp added that although his "intra-abdominal bleeding" has stopped, "his lungs are still not strong enough to cope on itself due to the Adult Respiratory Distress Syndrome and secondary lung infection".
At the time of the shooting, local reports said Drotske was visiting family with business partner and fellow former Springbok Os du Randt when they were attacked by four men. The latter was not injured.
Drotske won 26 caps between 1993 and 1999 and played one game during South Africa's home World Cup victory in 1995. He also played for London Irish from 2001-2003.
After retiring he coached Super Rugby side the Cheetahs before quitting rugby in 2015 to pursue business interests.