Welbeck (hamstring), summer signing Mwepu (knock) and Maupay (shoulder) will all be assessed after Brighton's final pre-game training session.
Tariq Lamptey will speed up his recovery programme from a hamstring problem during the international break.
Everton are without forward Moise Kean and midfielder Fabian Delph.
Kean is suspended after his sending off against Huddersfield in the Carabao Cup while Delph has a shoulder problem.
Alex Iwobi will be assessed after suffering an abductor problem and out-of-favour midfielder James Rodriguez is again unlikely to be involved.
Provisional Brighton squad: Sanchez, Webster, Duffy, Dunk, Gross, Alzate, March, Mwepu, Bissouma, Trossard, Maupay, Steele, Karbownik, Mac Allister, Lallana, Moder, Zeqiri, Caicedo, Richards, Connolly, Welbeck.
Everton provisional squad: Pickford, Begovic, Coleman, Mina, Holgate, Keane, Godfrey, Digne, Iwobi, Townsend, Doucoure, Allan, Gomes, Gray, Davies, Gbamin, Nkounkou, Kenny, Branthwaite, Richarlison, Calvert-Lewin.