England scrum-half Ben Youngs could be out for up to three months following surgery on his injured shoulder.
The 22-year-old, who scored two tries in last weekend's second Test loss to South Africa, has been forced to fly home after also suffering injury in the Johannesburg clash.
Youngs' second-half double helped bring England back within four points at the former Ellis Park before a late touchdown from JP Pietersen secured a 36-27 victory and a series win for the Springboks.
Youngs suffered the injury attempting to tackle Pietersen, whose try ensured the Springboks will take an unassailable 2-0 lead into Saturday's third Test in Port Elizabeth.
The Leicester player wrote in his column in The Times: "The prognosis is two to three months.
"There was a lot of discomfort and I couldn't really sleep on Saturday night, only on my back.
"On Sunday morning, I had medical screenings, had the scan and they came back with the result. The injury requires keyhole surgery."
Youngs faces stiff competition for his place, with Lee Dickson and Danny Care now vying to replace him in the side for the third Test in Port Elizabeth this weekend.
Youngs said: "It is gutting to miss the third Test - no-one likes to go home injured.
"I felt that at Ellis Park I had started to lay down a marker and gone and got the shirt back and then you are injured. It is so tough."