Left-back Lee Hills, winger Kieron Cadogan and striker Stern John all missed Sunday's FA Cup tie against Aston Villa due to having played in the competition for other clubs this season.
However, all three men now come into contention to face the Royals while defender Matt Lawrence will also hope to play some part.
The 35-year-old centre-back has been struggling with a hamstring strain and was an unused substitute against Villa.
He will be assessed ahead of Reading's visit as the Eagles bid to ease their relegation worries following their 10-point deduction for entering administration.
Kick-off at Selhurst Park is 8pm.
