The centre-back was named as player of the round after his goal knocked out Everton in the previous round, but he suffered a groin injury after just 15 minutes in the midweek win at Ipswich.
He will be given as long as possible to prove his fitness, but manager Brian McDermott will field veteran Ivar Ingimarsson if required.
Winger Jobi McAnuff could return from an ankle injury, while right-back Andy Griffin has been sidelined for the last four matches with an Achilles injury.
Goalkeeper Adam Federici is still out with a knee injury, so 21-year-old Alex McCarthy will continue to deputise.
On-loan QPR midfielder Mikele Leigertwood has permission to play and will look to add to his club record of 17 appearances for the Royals without tasting defeat. Defender Chris Armstrong was forced to retire this week as he battles multiple sclerosis.
Source: PA
Source: PA