The Us will be without key duo James Constable and Jake Wright for their top-of-the-table clash this weekend.
The second-placed U's welcome the League Two leaders without striker Constable, who has chipped a bone in his foot, and Wright who has undergone an operation on a groin problem.
Both players are set to be sidelined for at least a month and they join Jon Meades in the treatment room.
Wright's absence means Johnny Mullins will be partnered by Michael Raynes while Deane Smalley is pushing for a start. There is positive news about Sean Rigg who hopes to return to training in the build-up to the clash.
Chesterfield have no new problems ahead of their top-of-the-table clash with Oxford.
Blues boss Paul Cook, who will still be without defenders Nathan Smith (ankle) and Matty Brown (hamstring), must decide whether to make changes to a winning team after seeing the Spireites stretch their advantage at the summit of League Two to four points with a 2-0 home success against AFC Wimbledon last weekend.
Gary McSheffrey made his debut from the bench and will be pushing for a start along with fit-again club captain Ian Evatt and in-form striker, in the reserves at least, Eoin Doyle.
The likes of Sam Togwell, Armand Gnanduillet and Ryan Edwards are also options for Cook.