Leeds striker Luciano Becchio appears unlikely to win his fitness battle.
The Argentinian, forced out of the action after stepping off the bench in last week's home draw with Watford due to a hamstring problem, has had a second scan to determine the full extent of damage.
Manager Simon Grayson said: "It's looking like he has a slight hamstring injury so he'll be a doubt, although knowing him he'll want to play.
"If there's any doubt, we're at a too important stage to start running risks. If he doesn't play Friday, we've got another game on Monday."
Grayson, who has no other new injury or suspension problems, has plenty of options up front, with Davide Somma, Billy Paynter, Ross McCormack and Sanchez Watt all in contention.
Watt has returned to training following an unspecified problem but winger Lloyd Sam is still struggling with a knee injury.
Reading could be unchnged as they look for a ninth straight win.
Brian McDermott's men have stormed to within three points of second place thanks to their fine form and the manager could name the same XI who beat Leicester 3-1 last weekend.
Captain Matt Mills has returned to the heart of the defence after a month out with a groin injury and forward Noel Hunt marked his comeback from a foot injury with a goal as a substitute last week.
Goalkeeper Adam Federici is back after nine games out with a knee injury but has been restricted to a place on the bench due to the form of England Under-21 international Alex McCarthy.
Alex Pearce is fit after a thigh injury while fellow defender Sean Morrison has been recalled early from his loan spell at Huddersfield.