Three points was snatched out of Fleetwood Town boss Uwe Rosler’s hands by Ethan Ebanks-Landell’s last-gasp injury-time header.
Town had punished an early United mistake as Long swooped on a tame back-pass and his angled effort was cleared off the line straight to David Ball who gobbled up the opportunity to fire into an empty net and bag his fifth goal of the campaign.
United and Town both had chances with both keepers Chris Neal and Simon Moore playing out of their skins.
And after a late onslaught the Blades final found their killer touch as Ebanks-Landell popped up in the fifth minute of injury-time to nod in substitute Chris Hussey’s left wing cross.
The point ends Town’s three-match losing streak but saw despite the draw they dropped from 13th to 14th in the League One table.
Fleetwood’s injured duo Long and Dempsey returned to the starting line-up in place of Devante Cole and Eggert Jonnson as Rosler made two changes to the side that lost 2-1 at Bradford.
United made the brighter start to the game as Fleetwood adapted to a new 4-4-2 formation.
And United should have taken the lead in the third minute as Duffy sliced through Town’s middle with a through ball down the channel for Done to nip in-between Duckworth and Pond and sprint one-on-one with Neal but fortunately the keeper was on hand to smother the ball.
But it was Town who broke the deadlock against the run of play, Chris Long pounced on a sloppy back pass and steamed into the box on the left, drew the keeper out and his angled strike was cleared off the line straight into the path of Ball who kept his composure to fire into an empty net in the 13th minute.
Conor McLaughlin was booked for trying to kick the ball out of the keeper’s hands and up the other end Neal pulled off a fine fingertip save to tip over Billy Sharp’s chip as the half wore on.
The goal reinvigorated Town who absorbed United’s pressure and launched a number of fine counter-attacks.
The best of the lot was an effort from Ball from the edge of the box that was just batted away by Neal after a great break by Ryan with Dempsey also going close as he single-handedly took on the Blades defence but his curling effort was just palmed round the post by Neal as Town searched for a second goal.
It was end-to-end in the second half with both sides playing impressive counter-attacking football.
Long and Ball produced a moment of magic as they cut through the Blades defence like a hot knife through butter to allow Long to sting the palms of Moore once again, the follow up eventually fell to Grant who just curled the ball over the bar.
United went close twice as Neal made another good save with his legs to stop Fleck’s effort and Sharp diverted the ball wide at the back stick.
Neal was booked for time wasting as ex-United player Martyn Woolford entered the fray to a bad reception from the travelling Blades fans.
Hunter came off the bench for Ball and was in the action straight away as Duckworth slipped the ball inside from the right but his first-time angled shot was blocked out of play.
Up the other end Done nodded Chris Hussey’s left wing cross wide at the back stick when he should have hit the target.
Jonsson was brought on in the centre of midfield to try and halt United’s attacks as Town went 4-5-1 with Hunter playing as a lone forward.
Hunter was booked as Town weathered yet another United corner.
But Town nearly scored in the 85th minute as Woolford pranced down the left and fizzed the ball in towards Hunter who’s diving header was just tipped away by Moore.
Jonsson was booked for tumbling Sharp and United took the subsequent set-piece short with Eastham making a vital headed clearance at the back stick and another tantalising United corner was just cleared from danger by Town.
It was a nervous final few minutes to the game as United continued to win corners and camp in Town’s half, Rosler’s men battled the onslaught but the Blades finally broke through Town’s armour in the final minute as Hussey’s cross from the left was nodded in by Ethan Ebanks-Landell in the final minute of the five minutes of injury time.
Fleetwood: Neal, Duckworth, Pond, Eastham, Bell, McLaughlin, Ryan (Woolford, 60), Grant, Dempsey, Ball (Hunter, 66), Long (Jonsson, 77). Subs not used: Cairns, Jonsson, Bolger, Cole, Jakubiak.
Sheffield United: Moore, Fleck, O’Connell, Sharp, Done, Wright (Scougall, 58), Coutts, Freeman, Freeman, Ebanks-Landell, Duffy (Chapman, 67), Lafferty (Hussey, 52). Subs not used: Ramsdale, Brown, Wilson, Whiteman.
Referee: A Haines.