Peter Taylor said: "We're hopeful it's not too serious. We think there is a fair chance he will be fit for next Saturday."
Keates or Richie Appleby could be a straight swap for the midfielder, while Richard Hinds or Damien Delaney could move from defence to midfield. Whoever is chosen is likely to partner Stuart Green in the centre of the park. Green was signed from tonight's opposition back in December, but never made an appearance for the Magpies' first team.
Other than replacing Ashbee, Taylor doesn't have to make any further changes to the side that beat Leeds. Ryan Williams (illness), Andy Dawson (knee) and John Anderson (foot) are still out.
Expected line-up (4-4-2): Fettis; Thelwell, Hinds, Joseph, Delaney; Price, Green, Keates, Elliott; Allsopp, Burgess.
Subs: Musselwhite, Whittle, Burton, Regan, Melton, Appleby, Fry, Donaldson, Webb.