Williams and Phillips were listed as doubtful on Saturday. Williams said that he didn't expect to play after missing the previous five games.
Phillips, though, said last week he expects to play against the Redskins after aggravating a MCL injury that had kept him out of six games. A source said he looked a bit tentative while running in the past couple of practices.
Phillips may test his knee before the game on Monday night.
Williams and tight end Travis Beckum (knee) are the only Giants who are out for the game and did not make the trip. Beckum was ruled out on Saturday with soreness in his surgically repaired knee.
Defensive end Jason Pierre-Paul is listed as questionable with a back issue, although coach Tom Coughlin expects Pierre-Paul to play barring a setback.