South Africa lock RG Snyman underwent ankle surgery on Tuesday and will miss the opening months of Super Rugby, his Bulls franchise said.
Snyman returned at the weekend from a brief stint at Honda Heat in Japan where he injured his ankle.
Scans on Monday revealed more serious damage than initially anticipated and surgery was recommended, officials said.
The 2.07m tall second rower is not expected to be available again in April in the latest injury blow to the Pretoria-based side.
Springboks Marnitz Boshoff, Travis Ismaiel and Marco van Staden are only set to return at the end of March, while hookers Edgar Marutlulle and Jaco Visagie are also out, meaning certain game time for newly signed Schalk Brits.
Visagie is expected to be back in six weeks' time.
