Pigott was sent home from training earlier in the week after feeling unwell.
Centre-back Darius Charles (hip) and defender Will Nightingale (knee) are stepping up their rehabilitation as they close in on a first-team return.
Ghana forward Kwesi Appiah continues his recovery from a hamstring problem, having not played since before Christmas.
Caretaker boss Derek Fazackerley looks set to take charge of the team again, with the appointment of a new permanent manager seemingly no closer after both Steve McClaren and Karl Robinson distanced themselves from the vacancy.
Ivo Pekalski, who is stepping up his rehabilitation from a cruciate knee ligament injury, played more than an hour in the Oxfordshire Senior Cup defeat at Oxford City, but the midfielder will not be rushed back into first-team action.
Midfielder Rob Hall (calf) and Joe Rothwell (hamstring) also both continue their recovery.
Pedro stepped off the bench to send Chelsea into the FA Cup semi-finals after they beat Leicester 2-1 at the King Power Stadium on Sunday evening.
RB Leipzig came from behind at the Red Bull Arena to end a run of four winless games and defeat Bundesliga leaders Bayern Munich 2-1 on Sunday.