Preston are set to be without strike duo Iain Hume and Neil Mellor.
Hume was omitted from the team which lost 1-0 at Walsall after picking up a hamstring strain on international duty with Canada, while Mellor is still feeling the effects of a crunching tackle on his ankle by Saddlers midfielder Adam Chambers.
Lilywhites boss Phil Brown told the Lancashire Evening Post: “At the moment there’s a question mark about how long (Hume) is going to be out.
“As for Neil, unfortunately I don’t think he will be able to play any part in the two games this week.”
Brown may instead opt to use strikers Jamie Proctor and Juvhel Tsoumou who led the line during last week’s penalty shootout win over Morecambe in the Johnstone’s Paint Trophy.
Midfielder Doyle Middleton and defender Scott Leather should be passed fit in time to face the Blades.
Meanwhile Sheffield United winger Matt Phillips is poised to make his first start for the Blades.
Phillips stepped off the substitutes’ bench in Sunday’s Steel City derby draw after signing on loan from Blackpool on Friday.
Blackpool team-mate Billy Clarke arrived at the same time in a similar deal and will also be hoping to play some part for the Blades after he was an unused substitute against Sheffield Wednesday.
Teenage central defender Harry Maguire faces a late fitness test after sustaining a knee injury on Sunday, so Lescinel Jean-Francois is on stand-by, but midfielders Lee Williamson and Nick Montgomery are available.
Williamson was replaced by Phillips at the weekend after receiving a yellow card and skipper Montgomery came through unscathed after making his first start since August.
The Blades are in seventh place and are chasing their first win in four league matches.