United suffered a second Checkatrade Trophy defeat in Tuesday night's encounter with Walsall at Bramall Lane.
Scott Laird and Amadou Bakayoko gave the visitors the lead and a late goal from Paul Coutts proved to be a consolation.
Boss Wilder made changes, handing full debuts to versatile defender Brown and teenage midfielder Brooks. Basham went back into the side (his league suspension did not count), whilst five from Saturday's draw at Fleetwood also started. Homegrown 18-year-old defender Semple was amongst the substitutes.
Following an uneventful start, the visitors opened the scoring with the game's first chance - both Bakayoko and LAIRD were allowed too much space and the latter forced the ball home at the back post from close range.
United's first chance saw Fleck rob McCarthy and despite the subsequent cross evading Done, the ball dropped to Brooks, who fired over.
For Walsall, Oztumer had a shot deflected wide and then tried his luck from 40 yards but the diminutive midfielder's shot sailed over Moore's crossbar.
Late in the half, United created a couple of chances but Done failed to connect with a cross from Brown and O'Connell's header from Duffy's corner was deflected over.
The early chances in the second half dropped for the visitors but Moore made a couple of impressive saves; firstly from Ginnelly, who cut in from the left, and then from Bakayoko, the striker was close to celebrating but his header from six yards was kicked away by the goalkeeper.
The striker did celebrate, though, moments later, as Walsall added a second goal. On the break, Laird's cross from the left missed its intended target but BAKAYOKO was backing up to beat Moore with a first-time left-foot shot.
United made a couple of changes to try and get back into the tie and one of the substitutes gave the home side a lifeline. From a left-wing corner, Walsall failed to clear and Brooks laid off to COUTTS, who directed the ball through a number of bodies, into the corner of the net.
Late on United applied the pressure, trying to force an equaliser. Done was crowded out as he looked to turn in a Brooks cross and the young midfielder was involved in the next move which saw Freeman cross for Basham, who saw his goalbound shot blocked.
Four added minutes gave United hope, Basham was added to the attack, but the Blades were unable to trouble goalkeeper MacGillivray late on.
Blades: Moore, Hussey, Fleck, O'Connell, Basham, Scougall (Coutts 58), Done, Brown (Freeman 69), Wilson (Whiteman 80), Duffy, Brooks.
Unused: Long, Sharp, Lafferty, Semple.
Walsall: MacGillivray, Edwards, Laird, McCarthy, Dobson (Chambers 84), Oztumer, Preston, Ginnelly (Shorrock 75), Bakayoko, Toner, Moussa.
Unused: Etheridge, O'Connor, Butterfield, Roberts, Cockerill-Mollett.