Bournemouth have suffered a double injury blow.
Captain Miles Addison this week discovered he will miss the rest of the campaign with a foot injury sustained back in November while fellow defender Tommy Elphick is set to miss the next four weeks.
Elphick suffered the knee injury in the defeat to MK Dons earlier this month and a scan revealed soft tissue damage.
New loan signing Marcos Painter is set to start again at left-back after making his debut against Preston.
Charlie Daniels, the regular in that position, saw a surgeon last week having sustained a fracture to a metatarsal but the injury needs to settle before a decision on an operation is made.
Meanwhile, both Ryan Fraser and Charlie Sheringham have now returned to training and the latter looks set to play for the Cherries' development side next week.
Only goal difference is keeping Eddie Howe's men off the top of League One ahead of this weekend's encounter.
Blades Danny Wilson could name an unchanged side.
United have won their last three games in League One and Wilson will be reluctant to tinker too much with his winning formula.
Loan striker Jonathan Forte faces a late fitness test having missed last weekend's 3-0 win over Colchester with a knock.
Fellow loanee Dom Poleon awaits his full debut after joining from Leeds last week and is pushing for inclusion alongside Dave Kitson and Jamie Murphy.
Defender Matt Hill is still pushing for a recall after his recovery from a broken jaw but may have to settle for a place on the bench again.
Wilson's side are one point adrift of leaders Swindon and have a game in hand over the Cherries in second place.