The Chiefs will be without the services of Tim Nanai-Williams when they face the Sharks in Durban on Saturday while Sonny Bill Williams could also miss the clash.
Nanai-Willams is on his way home due to a broken finger while Williams – who left the field for a concussion test midway during the first half after a clash of heads with Stormers prop Vincent Koch in Cape Town at the weekend – has been suffering from headaches.
Williams returned to play after being cleared and stayed on the field until he was substituted late in the second half.
But since the match, Williams is battling to recover from the blow.
"He hasn't recovered as quickly as we would have liked," Chiefs assistant coach Tom Coventry told Fairfax Media.
"He's had a few headaches, and he's under a bit of a selection cloud."
Coventry revealed that Williams is yet to start the concussion protocol, and if his condition doesn't improve within the next day he will not be in action in Durban.
"There's a pretty comprehensive list of events he has to go through to be able to play," he added.
"It's a five day process, so he'll have to make some progress by tomorrow, or even this afternoon."
Meanwhile, prop Pauliasi Manu is battling to overcome a rib injury.
Marty McKenzie has arrived as Nanai-Williams' replacement while Manu's injury is being monitored on a day to day basis.