Frenchman Robert Pires was ruled out midweek after Gunners boss Arsene Wenger decided not to take the risk on his ankle injury, though Wenger hopes Pires will be fit to face Manchester United on Wednesday night.
Veteran defender Martin Keown is a major doubt with a hamstring while Pascal Cygan will miss this game out to a suspension. It could be that Oleg Luzhny returns to take Cygan's place.
England International Ashley Cole could return after recovering from a hernia operation, however Wenger is in limbo as he his to decided whether or not goalkeeper David Seaman is fit enough to make his 1,000th professional appearance after a hamstring injury, if not Stuart Taylor will remain in goal.
The Blades has a bit of a crisis with there full-backs ahead of there short trip over the pennines to Old Trafford.
Phil Jagielka is rated 60-40 to play, though Neil Warnock believes that he will bit fit, meanwhile Robert Kozluk and John Curtis are 50/50.
Recently midfielder Macel Cas, who was bought from Nott's County a few months ago has been playing in that right-back position but sadly he is cup-tied and Warnock could struggle to put out a strong eleven on Sunday.
Also cup-tied is Owen Morrison who played for Sheffield Wednesday in there 4-1 defeat to Gillingham in round 3 and Dean Windass who played for Middlesborough against Chelsea in the same round.
Long term injury victims are Steve Yates, Iffy Onoura, Simon Tracey and recently Ben Doane (another right-back) will all miss the Old Trafford experience.
Prediction: Arsenal 0-0 Sheffield United (Blades win on penalties)
Blades-Mad are not 100% of the FA Cup rules but we believe that if the score is level after 90 minutes it will go into extra-time. Should the score still be level after extra-time we believe that it will go to penalties.
Arsenal | Taylor Luzhny | Campbell | Lauren | Vierra Parlour | Ljungberg | Toure | Sliva Bergkamp | Henry |
 Sheffield United | Allison | Kabba Tonge | Brown | McCall | Ndlovu Kozluk | Page | Murphy | Jagielka Kenny |
