The Blades are in the last eight of the Emirates FA Cup!
Substitute Billy Sharp headed home at the end of the first-half of extra-time to secure a last eight spot, after a George Puscas penalty had cancelled out David McGoldrick's second minute opener at the Madejski Stadium.
Boss Wilder made five changes for fifth-round tie in Berkshire, with Lundstram, Luke Freeman, McGoldrick, Mousset and Osborn all starting. Zivkovic was named amongst the substitutes for the first time.
On a perfect night for football, the Blades got off to the best possible start, taking the lead after just 90 seconds. Osborn was afforded space on the left and his cross landed right on the head of MCGOLDRICK who applied a composed finish from six yards out.
On 13 minutes, Reading had their first effort on goal and Henderson had to be at his best to deny Meite with a dipping shot from distance, but it was the Blades who continued to dominant possession and territory.
Either side of the half hour mark, United had chances to make it two, but Egan headed over from Freeman's inswinging corner, before failing to connect with Lundstram's set-piece from the other side. Then, McGoldrick was given time and space 30 yards, but Rafael was equal to his strike, palming it away to safety.
But on the stroke of half-time, Reading levelled, against the run of play as PUSCAS fired home from the penalty spot after Baldock was adjudged to have impeded Rinomhota as he attempted to connect with a ball in from the left.
The first action of note in the second half saw Rinomhota booked, before McBurnie was introduced in place of Mousset and his introduction had a positive impact on the Blades as the visitors had two chances in quick succession, in a pretty quiet second period. Firstly, McGoldrick headed over from Osborn's cross, before Freeman stung the palms of Rafael from distance.
As the clock ticked down, extra-time looked a real possibility as neither team could fashion any clear-cut chances in the final 10 minutes, despite the introduction of Sharp from the bench and ultimately 30 additional minutes would be required to find a winner.
The open 15 minutes of extra-time were largely uneventful, although Retsos was introduced in place of Berge, but in the additional minute of play the tie swung decisively in the Blades favour. Freeman engineered some space on the byline and stood up the ball up invitingly to the back post where SHARP did the result, producing a diving header that beat the despairing lunge of Rafael.
The hosts to their credited kept going until the final whistle, pushing the Blades back at the death, but thankfully Henderson was equal to a Gomes effort, before the same player saw a final shot go inches wide of the far post before referee Friend called time, to the delight of everyone of a red and white persuasion
Reading: Rafael, Morrison, Miazga, Rinomhota (Baldock 105), Swift, Obita, Ejaria (Gomes 98), Yiadom, Meite (McCleary 105), Olise (Masika 98), Puscas.
Unused: Walker, Moore, Blackett.
Blades: Henderson, Baldock, O'Connell, Basham, Lundstram, L. Freeman (Retsos 105), Egan, McGoldrick (Sharp 79), Mousset (McBurnie 61), Osborn, Berge (J. Robinson 98)
Unused: Jagielka, Verrips, Živković.
As it happened...
Referee Kevin Friend gets the action underway.
United hit the front inside two minutes, as McGoldrick nods home from Osborn's inch perfect cross from the left.
United enjoying plenty of possession, with Berge looking comfortable in a deeper midfield role.
Reading on the attack for the first time and Henderson has to be at his best to deny Meite from distance with a powerful dipping effort that was heading for the top corner.
United continuing to dominant posession, still leading 1-0 here in Berkshire.
First corner of the night for the Blades.
And it's nearly two. Freeman's inswinging corner to the near post is flicked on by Egan, but it lands on the roof of the net.
Another corner for the Blades and another sight of goal for Egan, but this time he fails to connect with Lundstram's delivery.
McGoldrick tries his luck with a left-footed effort from distance, but Rafael palms the shot away diving to his left.
Peanlty to Reading...
Baldock is adjudged to have fouled Rinomhota
Goal for Reading...
Puscas slots the ball home from 12 yards
One minute of added time to be played here.
It's all sqaure at the break here at the Madejski.
A penalty from Puscas cancels out McGoldrick's early opener.
We're back underway at the Madejski...
Free-kick for the Blades on the right, but it comes to nothing.
At the other end, Olise fires high and wide.
Rinomhota is booked for a foul on Freeman, which halted a potential counter attack.
First change for the Blades, with McBurnie replacing Mousset.
Concern for the Blades as Meite looks to get on the end of Swift's ball over the top, only for Henderson to collect.
McGoldrick, with another header comes close to restoring United's lead, but it's inches too high, with Rafael at full stretch.
Freeman tries his luck from distance having robbed Rinomhota, but Rafael just about deals with his shot.
Second change for the Blades, Sharp replaces McGoldrick
United pressing for a winner force a corner.
Lundstram delivers from the left, but it comes to nothing
Two minutes added time to be played.
We're going to extra-time at the Madejski Stadium.
It ends 1-1 after 90 minutes.
Extra-time is underway, United kicking right to left.
Berge is replaced by Robinson.
Meanwhile, the hosts make a double change themselves.
Rinomhota has a chance, but fires wide of the near post.
Billy Sharp heads home Freeman's cross at the back post in the final minute of the first period of extra-time.
United lead 2-1 with 15 minutes to play.
The second half of extra time is underway, United lead 2-1
Retsos is handed his Blades debut as he comes on for Freeman
Some concern for the Blades as McCleary breaks in behind, but Baldock clears the danger
Henderson saves from Gomes at the expense of a corner.
Then he claims Morrison's header from the resulting set-piece, under pressure from Puscas
Retsos is booked for a foul on swift
With time nearly up, Gomes comes within inches of forcing penalties, as one minute of added time is signalled.
United hold on to progress to the Emirates FA Cup quarter-finals, with Billy Sharp's header in extra-time proving decisive.