Alan Lee, Jimmy Juan and Fabian Wilnis all face fitness tests on Saturday morning before a decision is made on whether they are ready to face Preston at Deepdale. Lee and Juan were back in full training on Thursday but Wilnis remains out after injuring his knee in last weekend's 2-0 defeat of Leicester City.
Lee (hamstring) and Juan (groin) are more likely to be involved than Wilnis but the Town management will take no chances on the fitness of the Irish striker in particular with just under a quarter of the season still to play and the Blues in with a chance of a top-six finish.
Royle says Lee's situation will be carefully weighed-up: "We've got to balance the other nine games left against the need to have him on Saturday. The great thing is that he's in with a chance which a couple of weeks ago we didn't think he would be. I rather feel the decision will end up being his. That's not me avoiding the decision, I want him to play, but I don't want him to play at all costs."
Adam Proudlock is out of contention after aggravating his knee problem in the reserves on Tuesday, having impressed manager Steve McCall during the first half.
Sam Parkin and Jay McEveley continue their recoveries from ankle and medial knee ligament injuries, while Nicky Forster and Gavin Williams are both expected to miss the rest of the season after knee operations.
Jaime Peters is still out after hurting his knee at Wolves two weeks ago, while new loan striker Ricardo Fuller is suspended after picking up a booking in last weekend's game against Leicester. Royle revealed at his regular Thursday press conference that referee Paul Taylor has admitted he got the decision wrong and would have rescinded the card had that been an option available to him.
The Jamaican was yellow-carded late on against the Foxes for an alleged elbow on Joey Gudjonsson but video evidence clearly showed the Icelandic midfielder took a dive.
If Lee fails to make it, the Blues are short of striking options with Danny Haynes not yet fully fit and Dean McDonald and Billy Clarke the only other choices. Pushing Richard Naylor forward could be an alternative, but only if Fabian Wilnis is fit to take his place at centre-half with Sito coming in at right-back.
A more likely scenario in Lee's absence would be Darren Currie reprising his role behind Haynes with McDonald on the bench.
Royle, who says he has never experienced a more injury-hit season, says Preston boss Billy Davies has impressed him: "Billy's done a fantastic job, they're having a great season. Minimal spending and big selling, they go on and they are on a great run.
"I think they've lost two in a row, albeit a cup game against a Premier League side and a hard away game at Reading, but they're in top form and they'll be confident. It'll be a good football match, they're a passing side like ourselves and it would be a great one to win for us. It'll make a great statement if we close to within two points of them."
Preston have a number of suspension and injury problems with defender Chris Lucketti out for a month with a groin problem and Matt Hill, Youl Mawene and Callum Davidson all banned for one match after reaching five bookings.
Keeper Andy Lonergan (knee) and midfielder Adam Nowland (broken leg) are long-term absentees.
Saturday's referee is Eddie Ilderton from Tyne and Wear who has shown 65 yellow and three red cards in 27 matches this season. Ilderton's last Town game was the 1-1 draw with Sheffield United at Bramall Lane in April 2004.
Probable squad: Supple, Price, Wilnis, Barron, Sito, Richards, Naylor, De Vos, Garvan, Richards, Westlake, Juan, Magilton, Skard, Currie, Lee, Haynes, McDonald, Clarke.