Diego De Girolamo netted a first-half double as United returned to winning ways in the Professional Development League, with a deserved success over Watford at Vicarage Road on Monday night.
De Girolamo took his chances to put the Blades in the ascendency and it was a lead Chris Morgan's side never looked like relinquishing as Ryan Flynn and Terry Kennedy both completed 90 minutes against Harry Kewell's young Hornets.
The home side started positively though and the first chance fell to Byers in the fourth minute, but Eastwood was equal to his long-range strike, tipping the ball round the post.
But in the 15th minute United caught the Hornets cold to opening the scoring, a through ball saw DE GIROLAMO get in behind the home rearguard and he fired past Gilmartin having showed good strength to hold off the attentions of Rowan.
And five minutes later, the visitors doubled the advantage. A defence splitting pass from Wright freed Phillips who put an inviting ball across goal and DE GIROLAMO was in the right place at the right time to apply the finishing touch.
The home side were shell-shocked and De Girolamo was a live threat as he chased his hat-trick and a third goal for the Blades, whilst at the other end Lewis shot inches wide having cut inside from the left.
In Watford's next attack Mensah and Folivi combined before the latter shot straight at Eastwood from a promising position.
But it was United who came even closer to another goal in the last action of the half, only for Gilmartin to pull off the save of the game to deny Wright from the edge of the area.
The second-half was a quieter affair but just after the hour; only a timely intervention from Gilmartin prevented Flynn from getting his name on the scoresheet.
Watford were reduced to 10 men in the 81st minute when skipper Byers was given his marching orders for a second yellow card following a cynical foul to prevent a swift United break.
In the final moments of the game the impressive Eastwood made sure of a clean sheet when he parried an effort wide from long-range.
Blades: Eastwood, Phillips, Banton, Whiteman, Kennedy, Evans, Flynn, Dimaio, Wright (Gordon 78), De Girolamo (Heh 86), McDonagh (Hamilton 78).