Speaking after the match, South Africa head coach Heyneke Meyer revealed that the influential hooker faces an eight-month recovery.
"I think Bismarck will almost certainly be out for the rest of the year," said Meyer.
"He went for a scan and may have torn ligaments. I do not want to pre-empt anything before the doctors have the final say, but that type of injury normally rules a player out for up to eight months."
Craig Burden has been called up as a direct replacement for du Plessis.