The Irishman has undergone surgery on a shoulder problem and is expected to be out of action for around three months.
Manager Neil Warnock will also be missing midfielder Ben Watson, who is struggling with a calf injury.
But there is better news for striker James Scowcroft who is on the brink of returning from a torn hamstring and could claim a place on the bench.
Meanwhile, transfer-listed forward Shefki Kuqi is likely to feature after entering into negotiations with the club over a new deal.
Leicester boss Nigel Pearson looks set to name an unchanged side for the clash.
Matty Fryatt, recently named as the Powerade League One Player of the Month for December, made his return from injury in the 3-0 defeat of Leyton Orient on Saturday and will be fit to face the Coca-Cola Championship side on Wednesday.
The 23-year-old striker had missed the first game against Palace with an ankle injury.
Matt Oakley should also retain his place having made a goal-scoring comeback at the weekend.
Midfielder Mark Davies, who is on loan from Championship side Wolves, will be keen to build on his current form after earning praise from Pearson following his strike against Orient.