The Lions make two changes, both enforced, with the cup-tied Ben Marshall and Ben Thompson making way for Shaun Williams and Aiden O’Brien.
Thompson scored twice in Wednesday’s win over Birmingham.
Millwall: Martin, Romeo, Pearce, Cooper, Ferguson, Leonard, Wallace, Tunnicliffe, O’Brien, Williams, Gregory.
Subs: Amos, McLaughlin, Meredith, Hutchinson, Elliott, Morison, Skalak.
Chris Hughton makes just one alteration to the side that beat Crystal Palace last time out, with Beram Kayal replacing the suspended Yves Bissouma.
Anthony Knockaert has two goals and two assists in his last five FA Cup appearances and scored a stunner against Crystal Palace last week. He starts.
Brighton: Ryan, Montoya, Duffy, Dunk, Bernardo, Kayal, Stephens, Propper, Jahanbakhsh, Murray, Knockaert.
Subs: Button, Bong, Burn, Izquierdo, March, Locadia.