Kieron Freeman played over 70 minutes, as United's U23s made it three matches unbeaten with a draw against ten-man Leeds on Monday afternoon.
Jake Wright's second-half goal made sure the Blades got a share of the spoils and the home side dominated after cancelling out Sam Dalby's opener.
The game's first opportunity came eight minutes in and it went the way of Leeds as Dalby won an aerial battle and got in behind the defence to square for Machuca who blazed over the bar from two yards out.
Just a few minutes later the Blades came close as Hallam's corner evaded everyone and flew just past the post and the slightest touch would have seen the ball find the back of the net.
Very shortly afterwards it would be Hallam in the action as he was played in by a superb ball from Graham and the forward took the came within inches of netting.
But it was Leeds, who opened the scoring, as Hosannah got the better of Norrington-Davies on the right hand side and fired the ball across goal for DALBY to turn home and give the visitors the lead on 18 minutes.
United would respond soon after with Doherty sending Smith through on goal and he took his touch brilliantly but his shot was well saved by Huffer.
On the 34 minute mark the Blades missed a golden chance to go level as Smith put his effort wide, after Semple had freed Hallam.
After the interval United came out on the front front and had another great chance as Heneghan sent Hallam through with a great knock over the top. The initial effort hit the post, with Smith adjudged offside on the rebound.
Leeds goalkeeper Huffer would make to superb saves either side of the hour pushing shots from both Wright and Smith behind in an effort to maintain his side's advantage.
During this Blades onslaught Hallam would work his way into the box and curl an effort goal-wards but it was cleared off of the line.
With 17 minutes to go Leeds found themselves down to 10 men as Hosannah dived after beating Warhurst to the ball and picked himself up a second yellow card.
The Blades would finally find their equaliser on 79 minutes as Graham fizzed a great low cross in for WRIGHT to sweep home at the near post.
United continued to press in the search of a winner but Leeds were compact and hard to break down but a chance did arrive in the final three minutes as Semple headed just wide from a Hallam corner.
As the clock ticked over 90 a free kick was partially cleared and fell for Doherty who struck well but his effort agonisingly bounced off the post, as the Blades had to settle for a point.
Blades: Warhurst, Freeman (Portman 71), Norrington-Davies, Graham, Heneghan, Semple, Gilmour, Doherty, Wright, Hallam, Smith.
Unused: Dewhurst, Broadbent, Oure, Gordon.