Bradford's plans have been hit by a sickness bug that could rule out three unnamed players.
Manager Phil Parkinson cancelled training at the club's Woodhouse Grove training ground on Monday to try and prevent the virus from spreading throughout the squad.
Parkinson, who has no new injury or suspension problems, will be without on-loan Sunderland defender John Egan, who is ineligible to play, so Chris McHugh is likely to step in at centre-half.
The Bradford boss is expected to make several other changes as his side embark on their eighth game in the space of 24 days.
Strikers Nahki Wells and James Hanson were rested for the initial tie that ended 1-1, with Garry Thompson and Alan Connell forming a new-look attack and those two players could return for the replay.
Ricky Ravenhill and fellow midfielder Ritchie Jones (back), who did not travel with the squad for the weekend win at Aldershot, could also return.
Northampton will be without on-loan goalkeeper Lee Nicholls.
Nicholls has not been given permission to play by parent club Wigan, who also refused to let the 20-year-old feature in the Capital One Cup, so Shane Higgs is expected to start with Dean Snedker providing back up on the bench.
Jake Robinson enjoyed a goalscoring return to the Town side in the 4-2 win at Accrington at the weekend but the forward is ineligible against the Bantams having already played in the competition during his recent loan spell at Luton.
Midfielder Ben Harding will travel to west Yorkshire but it is understood his return to action will be delayed until the league game against Wycombe at Sixfields on Saturday.
