Cape Town - Stormers lock Eben Etzebeth faces "four to six weeks" on the sidelines as he recovers from the calf injury he picked up at training on Monday.
The Stormers confirmed that it is the same injury that had threatened to plague his 2015 Rugby World Cup.
The injury was sustained during a lineout training session, and Pieter-Steph du Toit and JD Schickerling will now start operate together in the second row for this Friday's clash against the Sunwolves at Newlands.
It leaves the Stormers a little thin at lock, where they have also lost Jan de Klerk to injury.
Reynhardt Elstadt will provide bench cover.
The other major injury blow to the Stormers came in the form of flyhalf Kurt Coleman, who tore his anterior cruciate ligament (ACL) and will be out for 9 months.
Scrumhalf Nic Groom is also ruled out for this weekend's clash with a knee injury.