The Blades moved back up to third after Reading were beaten 3-1 by Ipswich Town at Portman Road and in mean time Michael Brown fired home his 17th goal of the season to make it 2-1.
Former Middlesbrough striker Dean Windass put the Blades ahead on five minutes when Michael Tonge and Phil Jagielka combined to to put Deano in front of goal where his angled shot could not be saved by veteran goalkeeper Dave Beasant.
However the Seagulls hit back nine minutes later when Bobby Zamora skinned Robert Page to push a through ball past Paddy Kenny to leave midfielder Richard Carpenter a open goal to give the visitors a deserved equaliser.
But United's never say die attitude paid off when on 34 minutes, Danny Cullip brought down Michael Brown just 22 yards away from goal. The referee, Mick Fletcher (Worcestershire) delayed the free-kick but when Brown was given permission to take it he fired low under a wall made up of United and Seagulls players which was unstoppable to save as it went into the goal.
The second half could not live up to its previous but the away side did almost draw level but Bobby Zamora's shot was easily saved by Paddy Kenny.
United brought on Owen Morrison and Paul Peschisolido for Peter Ndlovu and Steve Kabba respectively.
The Blades came close to making it 3-1 when Owen Morrison dribbled around the defenders to go one-on-one with keeper Beasant, however the former Sheffield Wednesday midfielder's shot was somehow saved with the shot stoppers right hand which then went over the bar.
Another chance fell to a substitution with Paul Peschisolido and was given a great opportunity to capitalize when the defence opened up for him, is shot was goal bound but his shot was fantasticly saved.