The injury, which he picked up against Western Province over the weekend, immediately ruled the 29-year-old pivot out of the clash against the Eastern Province Kings on Saturday at Loftus Versfeld.
Prop Morne Mellett, who underwent a scope on his knee last week, has been ruled out for three weeks.
Strauss confirmed that flyhalf Tian Schoeman has recovered from injury, though, and would be fit for selection for the match in Pretoria.
Meanwhile, Dean Greyling (calf), Jurgen Visser (toe), Akona Ndungane (Achilles) and Lohan Jacobs (flu) remain doubtful but are expected to train on Tuesday.
Bjorn Basson would be available next week, but the likes of Pierre Spies, Flip van der Merwe, Arno Botha, Frik Kirsten and Jaco Visagie remain long-term casualties.