Farid El Alagui will be missing for Brentford.
The striker was taken off on a stretcher with a knee injury towards the end of Saturday's 2-1 league win over the Red Devils, and the Bees are waiting to discover the extent of the damage.
Clayton Donaldson ended his six-game goal drought with a brace at the weekend so he should keep his place up front alongside Paul Hayes.
Boss Uwe Rosler will rotate his squad with goalkeeper Richard Lee, defender Leon Legge and midfielder Sam Saunders hoping for run-outs.
"There will be changes, we have a heavy schedule and the priority is the league," said Rosler.
"But I want to make it absolutely clear that we will take the competition seriously."
Crawley will be without Claude Davis and Shaun Cooper.
Davis is sidelined with a thigh injury and fellow defender Cooper has a groin problem, with both players missing Saturday's 2-1 league defeat at Griffin Park.
Boss Richie Barker will name a strong side although changes are expected in attack with skipper Gary Alexander likely to be rested against his former club.
Nicky Ajose, Billy Clarke or John Akinde could come into the starting line-up while midfielder Dannie Bulman and winger Sergio Torres are also pushing for recalls.
Two more former Bees, right-back David Hunt and midfielder Nicky Adams, should be in the squad to face their old club.