Murphy will battle it out with Josh Lillis, who performed excellently at Millwall, for a starting place - while captain Crosby may struggle to get his usual position in the centre of defence after United kept another clean sheet at the New Den.
Other than in those areas no other changes are expected, although Ian Morris may miss out after being substituted early on in the Millwall win.
Manager Nigel Adkins could well decide to start Steve Torpey as part of a three-pronged attack after the forward netted the winner on Friday.
Chesterfield look poised to name an unchanged side from the one that drew 0-0 with Huddersfield on Saturday, meaning Caleb Folan will continue alongside Paul Shaw in attack.
The Spireites have lost just once in their last seven games.
Definitely missing for them are long-term absentees Alan O'Hare (broken ankle) and Jamie Lowry (glandular fever).