Colchester midfielder John-Joe O'Toole returns from a two-match suspension but striker Ian Henderson begins a three-game ban.
New signing Morten Knudsen will be in the squad if he gets international clearance in time.
Gillingham boss Mark Stimson told BBC Radio Kent:
"We're expecting a tough game. They are in a good position in the league and they have some good players for this level and a big physical element.
"We need to be ready for it, because it will be a challenge. The players have got to be ready, and I can't wait for Saturday to come round.
"Colchester play a certain way, and if we're not on the button then I think they could give us nightmares."
Source: BBC Sport