John Egan scored in stoppage time to salvage a replay for Sheffield United as the Blades drew 3-3 against non-league side Wrexham in a frantic fourth-round FA Cup tie at the Racecourse Ground.
Oli McBurnie headed home Tommy Doyle's cross to give Sheffield United the lead after just two minutes were played.
James Jones and Tom O'Connor scored inside the opening 20 minutes of the second half to put the Dragons in front before Oliver Norwood leveled for the visitors, who saw Daniel Jebbison sent off.
Paul Mullin seemed to have secured the non-league high-flyers progression to the fifth round in the 86th minute only to see Egan hit back late on.
Story of the match
Wrexham manager Phil Parkinson named an unchanged eleven from the side that moved to the top of the National League on Tuesday night.
Sheffield United boss Paul Heckingbottom made five changes from the team that beat Hull City as Ben Davies, Chris Basham, McBurnie, Ben Osborn and James McAtee were all recalled to the starting XI.
On just two minutes, a teasing delivery by Doyle found the head of McBurnie, who escaped his marker and he powered home a diving header at the near post.
Jordan Tunnicliffe was forced off straight after the goal and Aaron Hayden was injured inside of the opening ten minutes and also needed to be subbed off.
The Dragons thought they had a penalty as Mullin latched onto Anthony Forde's through ball and after being hauled down by Davies, but referee waved play on.
Mark Howard was called on to deny the advancing Jebbison and he parried away a speculative effort from Jayden Bogle in the 22nd minute.
Elliot Lee looked to have struck a volley that was destined to find the back of the net, but Basham made an all-important block.
Bogle then picked up a facial injury for an accidental clash with Ben Tozer and that resulted in seven minutes of stoppage time.
Mullin had Wrexham's two best chances of injury time, his first forcing Davies to parry and the second a free-kick blocked by the Sheffield United wall.
The opening minutes of the second half saw Davies spill a shot by Luke Young and saved the rebound by Mullin before Bogle eventually cleared.
In the 50th minute, Tozer's long throw wasn't dealt with and the ball bounced around the six-yard box before Jones was able to force home.
The Dragons then took the lead just after the hour mark as a left-wing corner by Young found its way to O'Connor, who arrived at the near post to slot home.
Less than four minutes after that, Norwood saw his initial shot blocked by Tozer, but he poked home the rebound.
Jebbison was then shown a straight red card in the 71st minute following an incident with Tozer and Sheffield United were lucky to have not gone behind, Ollie Palmer rattling the underside of the crossbar with Davies beaten.
Four minutes from time, Wrexham appeared to have found a winner as Mullin received a pass from Sam Dalby and calmly slotted under Davies.
Bogle was booked and with the Dragons seemingly headed to the fifth round, Egan snatched an equalizer, rising at the back post from a Doyle corner to nod home.
Player of the match: John Egan (Sheffield United)
