The Jamaican centre-half has missed the last two games with a thigh injury but resumed light training earlier in the week and has an outside chance of making the televised clash.
With Jose Fonte going off with a knock at Barnsley on Tuesday, Matt Lawrence still doubtful with a hamstring injury and Paddy
McCarthy not ready to return following his shoulder operation, boss Neil Warnock will give Davis until the last possible minute to prove his fitness.
McCarthy has been pencilled in for his comeback against QPR in a fortnight.
Warnock will stick with Shefki Kuqi and Antony Stokes in attack after allowing Alan Lee to join Norwich on loan.
Reading manager Steve Coppell is facing a difficult tactical decision ahead of the trip.
Coppell switched to a 4-5-1 formation at Doncaster on Tuesday and was rewarded with a much-improved performance which was capped by a late winning goal from lone striker Dave Kitson.
Top scorer Kevin Doyle put in a hard working shift out of position on the right wing while Stephen Hunt was dropped to the bench so Coppell faces a dilemma.
Cameroon international defender Andre Bikey was recalled ahead of Alex Pearce for his first start since January and should continue, while there is a doubt over winger Glen Little who missed out in midweek with a foot injury.
Goalkeeper Marcus Hahnemann is back in possession of the number one shirt after recovering from a torn calf muscle so Adam Federici will be forced to make do with a place on the bench.
Ivar Ingimarsson is out for the rest of the season with a knee injury while club captain Graeme Murty is sidelined with another calf injury. Strikers Noel Hunt and Leroy Lita - who have scored 20 goals between them this season - will hope to feature after not even making the final 16 at the Keepmoat Stadium.