Bulls forwards Dean Greyling and Wilhelm Steenkamp have been ruled out of Friday's Super Rugby opener against the Stormers in Pretoria.
According to the Bulls' official website, Greyling has a stress fracture to his foot, while Steenkamp is suffering from an AC joint injury, with team doctor Org Strauss saying they will not be able to play.
Steenkamp will still be out for another two weeks, while Greyling should be able to train next Monday.
This leaves Marcel van der Merwe as the only long-term injury casualty, with the former Cheetahs prop recovering from a knee operation. He should be back in action in May.
Dawie Steyn also started training this week following his leg fracture and will not be match fit yet.
Strauss said that a couple of players who did not train on Monday, including Ulrich Beyers, Akona Ndungane, Jacques du Plessis, Jacques Potgieter and Louis FouchÃ¨, will all be considered for selection.
Bulls coach Frans Ludeke will name his side on Tuesday.