The Blades came up against an in-form Fulham and the result could have been different had first half chances been taken.
Instead, Aleksandar Mitrovic scored two impressive first half goals and Tom Cairney added a third as the home side collected the points.
The United starting line-up displayed one enforced change with Donaldson replacing Clarke, who was suffering from a tight hamstring. Blackman recovered to take the 'keeper's jersey, leaving Moore to remain on the bench, where he was joined by the fit-again Brooks.
Basham and Duffy had early runs, testing the Fulham defence, and on 13 minutes the Blades went close as Lee Evans and Fleck were involved before Sharp peeled away from Odoi to head Duffy's cross over.
Blackman was also busy. He spilled a Cairney shot but collected from Johansen, after a big deflection off Basham, and Mitrovic.
Fulham, though, grasped the lead just after the half hour. Fredericks got behind the Blades defence and his low cross saw MITROVIC react first to poke home.
There was a great chance to level when Fulham were caught on the break but Bettinelli pushed Fleck's effort around a post and on 42 minutes an unmarked Donaldson failed to get a telling contribution to an Evans corner.
And within moments, Fulham had doubled their lead. Again MITROVIC was the difference, stabbing home at the front post after a neat ball down the left channel.
Mitrovic almost added a third in injury-time at the end of the first half but he sidefooted over after a blistering run from Sessegnon.
Brooks was introduced at the start of the second half as the Blades changed formation and the youngster was quickly in offensive mode but Bettinelli dropped on a loose ball ahead of Donaldson.
Johansen forced a save from Blackman but he could do little about Fulham claiming a third just after the hour. The home side won possession on halfway and after a quick break, skipper CAIRNEY added himself to the attack to score.
Boss Wilder threw on Ched Evans and Holmes in an attempt to offer different attacking intent and they almost combined soon after but the Welsh striker headed wide.
The only other Blades chance of note was Stearman having an effort blocked after free-kick, whilst Fulham held the ball professionally to keep the visitors at bay. Mitrovic wasted a chance for a hat-trick and Piazon went close.
Fulham comfortably saw out the closing minutes, plus four of added time, as United left the capital empty-handed.
Fulham: Bettinelli, Fredericks, Sessegnon, Odoi, McDonald, Johansen (Norwood 64), Cairney, Ream, Ojo (Piazon 58), Targett, Mitrovic (Fonte 86).
Unused: Ayite, Christie, Norman, Kamara.
Blades: Blackman, Baldock, Stevens, Fleck, O'Connell, Basham (Brooks 45), Sharp (Holmes 64), Donaldson (C Evans 64), Stearman, L Evans, Duffy.
Unused: Moore, Lundstram, Leonard, Lafferty.