The Scottish forward, who this week extended his loan deal from West Brom until Christmas, started against Nottingham Forest on Tuesday despite an ankle injury and was substituted at half-time.
With Alan Lee, James Scowcroft (both hamstring) and Calvin Andrew (knee) struggling, Shefki Kuqi - who scored as a substitute against Forest - is Palace's only other fit forward.
The injuries are also piling up in defence, with Clint Hill (knee) and Jose Fonte (back) missing the midweek defeat and Danny Butterfield, who has been out with a groin injury lately, also having to go off.
Mark Beevers, Marcus Tudgay and James O'Connor will all have late fitness tests ahead of Sheffield Wednesday's trip.
Defender Beevers (hip) is the more likely of the trio to prove his fitness, while forward Tudgay (groin) and midfielder O'Connor (hamstring) also hope to return.
Frank Simek made his first appearance for the Owls in 10 months when stepping off the substitutes bench against Plymouth in midweek.
The American, who returns to the ground where he sustained a severe ankle ligament injury in December last year, will be among the replacements.
Midfielder Jimmy Smith sits out the second of his four-match ban, but Richard Wood has shaken off the sickness bug that forced him off against Plymouth.
Akpo Sodje is likely to resume on the bench, while fellow striker Deon Burton and winger Wade Small are pushing for recalls to the starting line-up.