The defender was forced off in last week's 0-0 draw with Leicester due to a hamstring problem and will be assessed before the United fixture.
Tariq Lamptey impressed on his Seagulls debut in the same game and is fit to feature despite requiring stitches in a facial wound suffered during the match.
United boss Ole Gunnar Solskjaer has no fresh injury concerns.
The Norwegian made eight changes for Saturday's FA Cup quarter-final win at Norwich and looks set to make a similar number of alterations after the match went to extra-time.
Provisional Brighton squad: Ryan, Schelotto, Webster, Dunk, Burn, Propper, Bissouma, Gross, Trossard, Mooy, Maupay, Lamptey, Montoya, Mac Allister, Connolly, Stephens, March, Duffy, Murray, Button, Connolly.
Manchester United provisional squad: De Gea, Romero, Grant, Bishop, Dalot, Fosu-Mensah, Wan-Bissaka, Bailly, Lindelof, Mengi, Laird, Maguire, Shaw, Williams, Pogba, Matic, McTominay, Fred, Fernandes, Pereira, Lingard, Garner, Mata, Chong, James, Ighalo, Greenwood, Martial, Rashford.