Full-backs Fabian Wilnis and Matt Richards are still doubts ahead of Saturday's away game at Rotherham. Wilnis now looks less likely to be involved than was originally thought.
The Dutchman picked up a shin injury in the reserves last week which got worse after Saturday's match at home to Cardiff.
Richards returned from England U21 duty last Tuesday having re-opened a gash on his foot.
Manager Royle said: "I thought Fabian would be OK earlier in the week but we are not so sure now.
"It will be a case of hoping at least one makes it but at the moment, they are doubts for Saturday."
Better news is that skipper Jim Magilton came through just over an hour against Brentford without a problem: "There was no pain after the game and I'm confident it's OK now.
"I'll need some more rehab but the thigh felt good during the game and I'm well down the road to recovery now.
"Fitness-wise I felt OK but I need to get a lot more training under my belt."