The potential FA Cup fifth round home tie against either Manchester United or Cambridge United will be broadcast live on BBC1.
The winners of the replay between United and Preston North End at Bramall Lane on Tuesday 3rd February, will play the winners of the Old Trafford replay on Monday 16th February, kick-off 7.45pm.
Should the Blades beat North End and progress to the fifth round, then it will have implications on the Sky Bet League One fixtures against both Bristol City and Notts County, currently scheduled to take place on Saturday 14th and Tuesday 17th February respectively.
A fourth round replay victory over Preston North End will earn the Blades a home tie against either Manchester United or Cambridge United in the fifth round of the FA Cup.
The draw took place live on the BBC's One Show on Monday evening, with Gary Lineker and Alex Jones drawing the balls.
The number six ball was the penultimate ball drawn and will face either Premiership giants Manchester United or League Cup Cambridge United
North End and United drew their fourth round encounter at the weekend - Diego De Girolamo netting for the Blades.
John Cain, of United's Official Supporters' Club, represented the Blades at The One Show, accompanied by a selection of London-based Unitedites.
United's fourth round replay against Simon Grayson's Preston will take place on Tuesday 3rd February, kicking off at 7.45pm. Fifth round ties will take place across the weekend of 14 and 15 February 2015 - the weekend the Blades are scheduled to travel to Bristol City in Sky Bet League One.
The Blades beat Crewe Alexandra, Plymouth Argyle and Queens Park Rangers to reach the fourth round stage.