Nche, 30, was injured early in Saturday’s 61-7 victory against Japan at Wembley Stadium and returned to South Africa on Sunday to undergo scans to determine the extent of the injury, SA Rugby said in a statement.
He twisted both his knee and ankle at a ruck and was on crutches after the game.
Ntlabakanye, who made his test debut in July against Italy, had been in London playing for the Barbarians against the All Blacks XV at Twickenham on Saturday and joined up with the Springbok squad, which departed for France on Sunday.
The 26-year-old had been left out of the South Africa squad in the Rugby Championship after being issued with two formal doping charges by the South African Institute for Drug-Free Sport.
SA Rugby in August said there had been an “adverse analytical finding” in random testing but that Ntlabakanye disputed committing a doping offence. He is free to play until a hearing in December.
The Springboks take on France in Paris on Saturday in the second of five November test matches. They also play Italy on November 15, Ireland on November 22 and Wales seven days after that.
