However, defender Jason Crowe should be fit for the Cobblers after he emerged unscathed from his weekend appearance despite carrying a slight groin problem.
Fellow defender Adam Watts is again ruled out as he looks to shake off a bout of concussion, however he should be fit to face Bristol Rovers on Saturday.
Gray also has a selection worry over keeper Paul Walker after he sustained a hand injury last week. The Welsh stopper is unlikely to make Tuesday's game but should be in contention for the clash with Rovers at the weekend.
Walker's absence will mean Gray will be unable to name a back-up stopper among his substitutes.
Full back Lee Peltier is again expected to start in Yeovil's defence in place of injured player-manager Terry Skiverton.
Skiverton (foot) sat out Saturday's 1-0 home win over Swindon.
His position in the middle of the back four went to Peltier, who was switched inside, while on-loan Tottenham youngster Danny Hutchins was recalled at right back.
Skiverton also handed a debut to on-loan Bristol City midfielder David Noble, who is set to keep his place, as Yeovil recorded their first win since the new manager took charge eight games ago.
Fourth from bottom Yeovil head into the match level on 42 points with their relegation rivals, who drew 1-1 at Carlisle on Saturday.
Sporting Life