Blue Bulls prop Morné Mellett has been ruled out of rugby for the next six months at least due to injury.
The 26-year-old is suffering from vertebral artery dissection and will not return to the field again this year.
The injury is a flap-like tear of the inner lining of the vertebral artery, which is located in the neck and supplies blood to the brain.
Props Justin Forwood (rib), Neethling Fouche (ankle) and Dayan van der Westhuizen (shoulder) are also out of action at the moment and will return to the training field in two weeks, Blue Bulls team doctor Org Strauss confirmed.
Full-back Jurgen Visser has been cleared to return to the training field next week. Visser is returning from a hamstring injury that ruled him out of Friday's match against the Canon Eagles in Japan.
Pierre Schoeman (knee) and Ruan Steenkamp (knee) are set to return to action in three weeks.
Duncan Matthews and Ryan Nell should be able to play again at the end of August, following knee surgery.
Irne Herbst(knee) and Piet van Zyl (knee) are out for the season, as is Dennis Visser (ankle).