James Mortimer 02.May.2013Getty Images
Kahui has undergone a series of shoulder reconstructions in recent years, and fingers will be crossed that the injury is minor as the World Cup winner waits medical scans.
Chiefs coach Dave Rennie told the Waikato Times he wasn't overly positive.
"It's not very good," he said.
"The issue is around his shoulder now," with Kahui out of action recently with a hamstring issue.
"The medics are referring him to have another scan because he's got pain in his shoulder, the one that was operated on."
The Chiefs are scheduled to play the Rebels this weekend on Friday.
Kahui earlier this year revealed he would shift to Japan at the end of the Super Rugby season, signing a two-year contract with Toshiba club.
The injury was sustained during training when Kahui "felt a pop" when throwing a pass.