Leicester City have the upper hand already after the top flight club knocked the Blades out of the League Cup, winning by four goals to one at the Second Round stage at Bramall Lane.
United had secured their place in the 5th Round of the FA Cup having beaten fellow Championship opposition Ipswich Town (away) and Preston North End (home). Both resulted in a 1-0 victory with Nathan Thomas netting a spectacular goal at Portman Road and Billy Sharp scoring from the spot against the Lilywhites.
With the potential to earn a replay or better, boss Chris Wilder may be tempted to field a full strengh side at the King Power Stadium. However they will be without goalkeeper Simon Moore who is severing the second of a three match ban after being dismissed at Wolves. Midfielder John Fleck is also suspended, having picked up ten yellow cards and a red (so far) this season.
United may be boosted by the return of forward David Brooks after recovering from glandular fever.
The Foxes booked their place in the 5th round having won 5-1 at Peterborough United. Having drawn 0-0 at Highbury, City made history in the Third Round Replay against Fleetwood Town. They beat the Cod Army 2-0 in normal time but striker Kelechi Iheanacho became the first player in history to be awarded a goal by video assistant referee (VAR). The referee had initially ruled the goal out for offside before being overturned by a video replay.
The hosts are expected to recall winger Riyad Mahrez after he was dropped from the first team after issuing a transfer request - hoping to force a deal to Manchester City on transfer window deadline.
Meanwhile defender Wes Morgan could feature for the first time since New Year's Day.