The Lions captain Warren Whiteley injured his shoulder in the third and final Test in Port Elizabeth on Saturday.
Whiteley came on as a replacement and scored one of the three tries that kept the series, after trailing 26-10 with twenty minutes to go they snatched a 32-26 victory in the end.
A scan on Monday revealed a grade three injury to his right AC joint which will see him sidelined for up to six weeks.
The specialist confirmed on Tuesday that he does not require surgery yet.
Fellow Springbok Jaco Kriel will captain the Johannesburg side until Whiteley returns.