By Nick Said
Mapimpi was injured in a clash of heads with Augustine Pulu in the Springboks’ 49-18 Pool B victory over Tonga in Marseille on Sunday, which edged them closer to a quarter-final place.
The incident was reviewed by the Television Match Official, but not sanctioned with a yellow card.
"Makazole is out of the World Cup," Erasmus told reporters. "We know who we want to replace him, I would love to tell you who it is but we first need to notify World Rugby.
"It is very sad, it was an accident, but he has a fractured eye socket and he is out for four to six weeks. We will miss him because he is a brilliant rugby player and a fantastic person."
While no longer first choice in the side, Mapimpi has bags of experience having played a central role in South Africa’s 2019 World Cup victory in Japan.
"If we get to the final we will fly him back to join us here. It is sad but that is the game of rugby, these collisions happen," Erasmus added.
South Africa must wait until Saturday’s game between Ireland and Scotland in Paris to learn their quarter-final fate, but are in a strong position.
The only way they can be knocked out of the tournament is if Scotland beat top-ranked Ireland by 21 points or more and the latter get a bonus point for tries scored.
👐 Carries: 13— SuperSport Rugby (@SSRugby) October 1, 2023
📈 Meters made: 34
💪 Tackles made: 11
Deon Fourie scoops the Player of the Match award after a brilliant performance in a physical encounter.
If Scotland win by eight points or more with no Irish bonus point then they and South Africa advance.
"We would rather sit here than be Ireland, who have been number one in the world all this time and Scotland just have to beat them by eight points and they are out of the tournament," he said.
"Of the three teams, we are probably the most comfortable."