After an impressive start to 2015, United's U21s are currently in the middle of a sticky patch.
Chris Morgan's side kicked off the year with five successive wins but Thursday night's game at Bramall Lane was a third consecutive defeat, despite some encouraging signs in places.
The Blades started well with chances early on. Hamilton fired just wide and Whiteman's shot was spilled but the home side were unable to take advantage of the rebound, whilst Crewe recovered from the early scares to take the lead with their first attack.
With 16 minutes gone, Dalla Valle got the better of McFadzean and from the resulting cross, a shot from Saunders was deflected kindly into the path of WATERS, who beat Willis from close range.
Despite the setback, United remained the better side. Coustrain won possession in midfield and drove at the defence before shooting wide and Hamilton almost beat Crewe goalkeeper Masters in a race to a loose ball. For the visitors Saunders tested Willis.
Before the break, Dimaio was blocked as he looked to get a shot away from a good position and then curled just wide with the final chance of the half.
McFadzean was moved forward for the second half and he saw plenty of the ball in the early stages but chances were limited. Whiteman's volley was saved and on the hour a left-footer from Dimaio clipped the top of the crossbar.
United were again the more assertive side and Cockerline would have been in the clear if he could have latched on to a stray pass from Kearns but just moments later Crewe doubled their lead. On 66 minutes, Kelly was adjudged to have fouled COOPER, who took responsibility for the resulting penalty and sent Willis the wrong way.
Despite the goals, United continued to have more possession and attempted to move the ball around the pitch. Dimaio had another effort blocked from Wallace's lay-off and McFadzean's appeals for a penalty were ignored, whilst on 76 minutes Whiteman was surprised when Dimaio's cross reached him and could only divert the ball over.
For the visitors, Cooper came close to his second when he blasted against the crossbar in the final ten minutes and Waters and Colclough also had late efforts but Crewe did grab a third, on 89 minutes, when SAUNDERS - son of former Blades striker Dean - was sent clear to beat the exposed Willis.
As a measure of United's luck, in the third and final minute of injury-time, Hamilton's shot hit the inside of a post but still came out to protect Crewe's clean sheet.
Blades: Willis, Scarisbrick, McFadzean, Dimaio, Evans, Kelly, Hamilton, Whiteman, Cockerline (McDonagh 67), K. Wallace, Coustrain (Paling 45).
Unused: Eastwood, Hardy, Heh.