United's U18s warmed up for Wednesday's FA Youth Cup tie at Preston North End, but earning a deserved point against Leeds United at Shirecliffe on Saturday.
Defender Joseph Cummings headed home a late header as a youthful Blades side more than held their own against strong opposition who were at full strength.
United enjoyed the better of a pretty even first-
half and had a chance in just the sixth minute. Mallon engineered space out wide, but his inviting centre agonisingly flashed across the face of goal.
The Blades continued to press as the first period progressed and Hallam had two sights of goal in quick succession, with Mallon the architect, but on both occasions the in-form striker fired narrowly over the crossbar.
And the visitors caught the hosts cold from a corner in the 43rd minute to take a lead into the interval, slightly against the run of play.
The second-half followed a similar pattern to the first, United pressed for a goal, but the visitors defended resolutely.
Slater flashed an effort wide, before Smith was denied by the Leeds goalkeeper just after the hour. But with 16 minutes remaining, United got a goal their efforts deserved, with CUMMINGS heading home at the back post from Mallon's excellent left-wing delivery.
And it was United who came closest to snatching a winner but Hallam saw his free-kick saved and the loose ball was cleared.
On the stalemate, Lead Coach Derek Geary remarked: "It was a good point and a deserved one against a very well organised and much older side.
"It was a keenly contested derby and a draw was a fair result."
Blades: Perryman, Portman, Charlesworth, Hawkes, Cummings, Broadbent (Gilmour 56), Smith, (Greaves 81), Slater, Mallon, Hallam, McCarthy (Burton 56).
Unused: Ford, Stewart.