The Royals’ chief scout has been placed in charge of first-team affairs following the departure of manager Brendan Rodgers.
Rodgers left the club by mutual consent on Wednesday evening after little more than six months in charge, with first-team coach Dean Austin and football consultant Frank Lampard Sr following suit.
McDermott will be able to welcome back Shane Long after a three-match suspension, while fellow striker Simon Church is hoping to recover from a back injury in time to face the Robins.
Ryan Bertrand is also hoping to return to the fold after missing last weekend’s 1-1 home draw with Scunthorpe through illness.
However, Reading will be without long-term absentees Noel Hunt (knee) and Brian Howard (jaw).