Stormers utility back Dillyn Leyds will be sidelined for around nine months after tearing his anterior cruciate ligament, while Jano Vermaak is also set for a spell on the sidelines.
The 23-year-old, who can operate on the wing or at full-back, will undergo surgery after suffering a serious injury in training last Tuesday.
Scrum-half Vermaak sustained a neck disc injury in the Super Rugby defeat to Sharks this month and Stormers revealed that the damage is worse than initially suspected.
Vermaak required an operation last week and is now is expected to be out of action for three months, while Cheslin Kolbe will be monitored after the full-back suffered concussion in the win over Jaguares on Sunday.
There is more positive news of Damian de Allende and Rynhardt Elstadt, who returned to training earlier than anticipated and could be back in action against Sunwolves on April 8.