The pair sustained injuries in the goalless draw with Bidvest Wits at Sisa Dukashe Stadium this past Tuesday.
Team physio Mark Anderson told the club's website: "Rhulani got a knock on his head towards the end of the game in East London, and as a precaution he will not be available for the Nedbank game. He was taken to hospital after the game for assessment and has not trained with the team since."
He added regarding Mbenyane: "This was due to a grade left AC joint injury after falling awkwardly in a tackle. He like Rhulani is a doubt for the next game."
However, Vusi 'Skheshe' Mncube and Bongani Kama should be available for selection again, while Siya Ngubane and Katlego Mashego are back at training.
Paseka 'Computer' Mako is also expected to return to the mix after being taken off at half-time against Wits as a precautionary measure with a slight hamstring strain.
Chippa coach Dan Malesela, who missed the stalemate with the Clever Boys due to ill health, has been given a few days off after recently being discharged from hospital.