The Dutch defender, who will be given a late fitness test, missed the final 16 Premier League matches of last season following a ligament injury suffered in January.
And Van Dijk has not been selected so far this campaign after handing in a transfer request during the summer when he wanted to join Liverpool.
Danish midfielder Pierre-Emile Hojbjerg is Saints’ only absentee ahead of the trip to Selhurst Park as he has returned to his homeland due to the birth of his daughter.
Provisional squad: Forster, McCarthy, Stephens, Bertrand, Targett, McQueen, Soares, Pied, Yoshida, Hoedt, Van Dijk, Bednarek, Davis, Tadic, Romeu, Redmond, Ward-Prowse, Lemina, Long, Boufal, Austin, Gabbiadini.
Richarlison has revealed how he heard of Marco Silva's sacking and admits the Watford squad can't explain their mid-season dip in form.