Robert du Preez has been ruled out with a torn pectoral muscle and will undergo specialist opinion regarding possible surgery.
The DHL Stormers flyhalf was the only major casualty from the team's final tour game against the Hurricanes in Wellington.
The Cape franchise is already without their first-choice flyhalf, Jean-Luc du Plessis, through injury.
Centre Dan du Plessis and flank Cobus Wiese have both successfully undergone surgery on dislocated shoulders, which have put them out of action for the next four months.
Centre Damian de Allende (ankle) and wing Seabelo Senatla (foot) will both return to full training this week after lengthy lay-offs, along with locks Eben Etzebeth (calf) and Pieter-Steph du Toit (knee), who have recovered from minor niggles.
Photo: Mark Tantrum/AFP Photo