The South Africa midfielder was stretchered out of Saturday's goalless draw against Ipswich amid fears he had broken his leg.
Scans have since shown there was no break but boss Steve Cotterill rates Mokoena as doubtful to figure at Selhurst Park so Richard Hughes could come back into the starting line-up.
Dave Kitson and Liam Lawrence made their debuts on Saturday after their deadline-day moves from Stoke and will continue along with striker Kanu, who made his first appearance of the season after finally resolving his contract dispute with the club last week.
Hermann Hreidarsson (Achilles), Danny Webber, Tom Kilbey (both knee) and Billy Goddard (shin) are still out.
Source: PA
