Bristol Rovers will be without defender Tom Parkes.
The 20-year-old was sent off against AFC Wimbledon which ruled him out of the trip to Accrington but as a result of an FA hearing he will be banned for an additional game following comments he made after his red card.
Manager Mark McGhee does have another defender available again in Michael Smith whose mystery abdominal problem meant he also missed the defeat at The Crown Ground.
Loanees Tom Eaves and Matt Lund have been cleared to play in the match while Shaquille Hunter will be available having been ruled out with a knee problem since early August.
On-loan Chelsea goalkeeper Sam Walker is also expected to get a chance to impress. McGhee told the Bristol Evening Post: "He's a good goalkeeper, but also has a fantastic mental strength about him. He's training even harder now and if he comes in on Saturday for the FA Cup game then he'll certainly deserve his chance."
Sheffield United manager Danny Wilson has hinted that he could ring the changes for their cup tie.
The Blades are flying high in League One and are second only on goal difference, having lost just one match in all competitions, and Wilson is not likely to compromise their promotion chances for cup glory.
Dave Kitson definitely misses out for the second match running with a hamstring strain, while defender Lescinel Jean-Francois is also unavailable due to a knee injury.
Goalkeeper Mark Howard remains sidelined with a thigh problem so 18-year-old George Long continues to deputise, with Wilson praising the teenager's efforts in the first team this season.
"George's development is all about decision making. I have said countless times before his shot-stopping is absolutely first class," he told the club's official website.