Midfielder Williams came off during the second half of Tuesday night's 2-1 win over Bristol City with a sore muscle but should be available.
Boss Ian Holloway also substituted winger Wilfried Zaha after he took "a couple of knocks" but he too is expected to be fine.
However, Palace still have a lengthy injury list with skipper Paddy McCarthy (groin) a long-term absentee and fellow defenders Joel Ward (groin) and Danny Gabbidon (hamstring) still struggling.
Midfielders Owen Garvan (knee), Andre Moritz (ankle) and Alex Nimely (hamstring) are also on the injured list.
Stephen Dobbie may have earned a start up front after his goalscoring cameo in midweek.
- Sports & Recreation
- Wilfried Zaha