Blades manager Kevin Blackwell refused to identify which player will miss the clash at Loftus Road, but confirmed midfielder Nick Montgomery will return to contention following a one-game suspension.
Striker Darius Henderson missed last week's win over Crystal Palace due to a hip problem and has now missed the last three matches.
On-loan pair Keith Treacy, from Blackburn, and Stoke's Andrew Davies have both returned to their parent clubs, but Blackwell has no new injury or suspension problems.
The Blades, unbeaten in their last six league games, could climb into the top six with victory if other results go their way.
