Recent signings Enoch Showunmi and Colin Healy, who missed out because of red tape, and suspended pair Darren Barr and Carl Finnigan are available again and are expected to go straight back in against United.
With Jackie McNamara having returned to action against Kilmarnock following a knee injury, May has only Tam Scobbie (pelvis) and Mark Stewart (groin) still sidelined.
Kick-off is 1.15pm.
Falkrik (from): Olejnik, Barr, McLean, Pele, Twaddle, Arfield, Lima, Flynn, Finnigan, Moutinho, Showunmi, Wagenaar, Healy, Compton, O'Brien, Bullen, Marceta, McNamara.
