The Bulls could be without three key players for this weekend's clash with the Kings, the Pretoria-based franchise announced on Monday.
Pierre Spies, Jano Vermaak and Francois Hougaard are all injured and in danger of missing Saturday's match at Loftus Versfeld - their first game after the international break.
"Spies has a grade three tear to his bicep picked up against Samoa on Saturday," the Bulls said in a statement.
"Vermaak is recovering from a hamstring injury picked up against Italy three weeks ago and Hougaard will see a specialist on Tuesday to look at his ongoing knee issue.
"Spies will also see a specialist during the week."
Arno Botha was a new inclusion in the long-term injury list following the knee injury he picked while up playing for the Springboks against Scotland two weeks ago.
Louis Fouche (quad), Dewald Potgieter (contusion) and Dean Greyling (bronchitis) did not train on Monday, but team doctor Org Strauss gave Travis Ismaiel (shoulder), Akona Ndungane (bone bruising), Jacques Potgieter (foot) and Lohan Jacobs (toe) the green light to practice with the rest of the squad.