Wright-Phillips - signed on a free transfer from Southampton earlier this summer - suffered a knee injury in a behind-closed-doors game and is set to be ruled out for six weeks.
It is the second injury blow for Argyle ahead of Saturday's clash at Selhurst Park, as centre-back Chris Barker is sidelined with a torn calf muscle.
Wright-Phillips' place is likely to go to on-loan Blackburn winger Alan Judge - who joined the Pilgrims on a season-long loan earlier this week - while new centre-back Reda Johnson, signed from French club Amiens last week, is poised for his debut in the back four.
Former Palace midfielder Carl Fletcher - who joined Argyle at the start of the summer from the Eagles - is set to feature for Paul Sturrock's side.
