Springbok halfback Fourie du Preez will be sidelined for four to six weeks after tearing a right knee ligament.
The Bulls confirmed Du Preez suffered a grade two medial ligament tear when his knee bent back awkwardly in the defending champions' victory over the Sharks on the weekend.
Du Preez, 29 and a 55-test veteran, should be fit for the start of the Tri-Nations in July.
AdvertisementAdvertise with NZME.
Latest from Sport
Back from the dead: Crusaders sound a Super Rugby warning
The previously winless champs appeared ready for a revival while beating the Chiefs.