Davies (hamstring) has missed City's last two games, while Clarke has missed the Bantams' last four matches with a knee problem, but the pair of them will be assessed again in the build up to Wednesday's tie.
Matthew Dolan could also be in with a shout of featuring after his own recent hamstring problem.
Loanee goalkeeper Jordan Pickford will certainly sit out the match though due to his red card against Rochdale on Saturday and the fact that parent club Sunderland don't allow the young shot-stopper to play for City in F.A Cup ties.
This all means that Ben Williams is expected to once again don the goalkeeper gloves for City at the Coral Windows Stadium on Wednesday night.
Young apprentice winger Dylan Mottley-Henry, who was on the City bench against Rochdale on Saturday, twisted his ankle in training on Monday and looks likely to miss out on the visit of Millwall.