Danny Wilson has a couple of injury concerns ahead of Tuesday night's League One clash with Walsall at Bramall Lane.
Dave Kitson (virus) and Marcus Williams (back and ankle) are both rated as touch and go to face the Saddlers.
The Gaffer confirmed: "Dave trained on Monday morning but we will continue to monitor him because the illness seems to have taken a lot out of him.
"Marcus took a couple of heavy knocks at Preston; he also trained but was moving gingerly so we will have to see how they both are on Tuesday."
Chris Porter and Shaun Miller would be the most likely candidates to replace Kitson, with Neill Collins on standby to fill the void left by Williams.
Lecsinel Jean-Francois (knee), not the one he damaged in March, is set to undergo surgery after tweaking his cartilage in the Johnstone Paint Trophy tie at Notts County.
Wilson has indicated the Haitian international will be sidelined for around two months.
Meanwhile, Walsall have extended goalkeeper Karl Darlow's loan from Nottingham Forest by a further two months.
The 21-year-old was signed following injury to Jimmy Walker, and he has gone on to play seven times since his move and is likely to continue on Tuesday evening.