In-form striker Adam Stansfield and new central defender Troy Archibald-Henville are both ruled out by knee injuries.
Stansfield is set to be out for up to a month, while Archibald-Henville is set to miss the rest of the season after injuring his knee in the warm-up before last weekend's 1-1 home draw with Southampton.
Grecians boss Paul Tisdale said: "Losing Troy is a massive blow to everyone at the club and most of all for Troy."
Stansfield is set to be replaced by Marcus Stewart, who missed the draw with the Saints due to a hamstring injury.
Playmaker Alex Russell (back) is ruled out for a second week running.
Veteran goalkeeper Andy Marriott is set to make his third successive start at the expense of Paul Jones.
