The Cottagers slumped to a 3-0 defeat at home to Southampton on Saturday and are without a win in four games but their deadline-day signings are ineligible to feature
The Cottagers' miserable season reached another low on Saturday when they dropped to the bottom of the Premier League table with a 3-0 home defeat against Southampton.
Rene Meulensteen's side is without a win in four games and has scored just one goal in those fixtures.
Hugo Rodallega found the back of the net to salvage a replay at Bramall Lane on Jan. 26 after 10-man United looked set to pull off a shock win.
Meulensteen has described the task facing him at Craven Cottage as the biggest challenge of his career to date and the Fulham coach could do with a morale-boosting win against Nigel Clough's League One side.
The Dutchman attempted to turn his side's fortunes around by bringing in several new faces during the transfer window. Greece striker Konstantinos Mitroglou will be expected to add some much-needed firepower following his move from Olympiacos but he, Larnell Cole, Lewis Holtby, Ryan Tunnicliffe, William Kvist and John Heitinga are all ineligible to feature on Tuesday as they were not registered when the original tie was played.
Fulham has doubts over John Arne Riise (hamstring), Fernando Amorebieta (knee) and Matthew Briggs (hernia).
Sheffield United also comes into the game on the back of a 3-0 defeat on Saturday, at the hands of Crewe Alexandra. Clough was puzzled by his side's lackluster display at Gresty Road against another side battling to avoid relegation.
United, which pulled off a stunning win at Aston Villa in the third round, is now without a win in four games across all competitions but gave Fulham a real scare when the two sides met in January.
Chris Porter put United in front, but its hopes of reaching the fifth round suffered a major setback when Michael Doyle was sent off early in the second half and Rodallega scored 15 minutes from time.
Porter has been struggling with a hamstring injury and was dropped to the bench at Crewe but the former Derby County striker could start at Craven Cottage. Doyle serves the second game of a three-match ban as a result of his dismissal in the first tie between the two clubs.