The Bulls captain Pierre Spies has had surgery on a torn bicep muscle and will miss the remainder of the rugby season.
The loose-forward picked up the injury playing for South Africa in their 56-23 victory over Samoa in Pretoria at the weekend and after being assessed by two specialists it was decided he needed to go under the knife.
Spies' absence means the Springboks must find another option at number eight for the Rugby Championship later this year, while it is also a blow to the Bulls' chances in Super Rugby, where they are currently placed third.
