Barnet were handed a cruel late defeat - made all the worse by a terrific second-half performance .
Doncaster dominated the first 45 minutes and went in 2-0 up thanks to goals from James Coppinger and Matty Blair.
A second-half assault, with Sam Muggleton’s long throw the key, saw Bees draw level in dramatic fashion through Bira Dembele and Luke Gambin.
Just as it appeared Allen’s side had snatched a draw on 85 minutes, Andy Williams popped up in the box to snatch a late win.
Rovers begun in the ascendancy with Matty Blair hooking an effort over the angle of right-hand bar and post after Michael Nelson’s headed clearance.
James Coppinger then probed the gap between Barnet’s defence and midfield and managed to put the home side into the lead after 15 minutes.
A defensive clearance fell to him 18 yards out and he took it first time, firing a fine volley into the bottom corner with Josh Vickers stranded.
The tempo slowed and allowed the visitors back in to the contest.
Dembele’s knock down from a free-kick fell to Jean-Louis Akpa Akpro, whose ambitious overhead kick wasn’t far from the left hand post.
Dembele won another attacking header but it sailed wide and John Akinde, well marshalled in the first half, nodded well off target from a set-piece.
Doncaster doubled their lead in the 32 nd minute with a well-worked goal.
Matty Blair exchanged a sharp one-two with Andy Williams, who played the former in on goal past a static Bees defence; Blair made sure with a calm finish.
Barnet showed as encouraging a reaction to their second concession as they did to their first, as Sam Muggleton’s prodigious long throws proved a consistent aerial threat due to their sheer distance and direction.
This continued to prove the case after half-time.
Bondz N’Gala’s sharp header from a Muggleton delivery was grabbed by keeper Marko Marosi, who sustained an injury in the process but was able to continue.
Another Muggleton tracer bullet, and Michael Nelson’s flicked header saw the ball strike the underside of the bar and was cleared for a throw-in; alas no relief for the hosts.
Muggleton’s angled throw from the far side found Dembele charging in and he placed a firm headed effort into the bottom left hand corner to make it 2-1.
The game hung in the balance with 20 minutes to go at which point substitute Jordan Amaluzor had a good chance to swing it one way only to see his clipped shot was palmed behind by Marosi.
The home frustration grew at referee Trevor Kettle’s perceived leniency at Barnet’s tough approach.
But Martin Allen’s side pulled level with five minutes to go with a goal that looked for all the world like they had earned a deserved point.
Muggleton played Akinde into the left-hand channel and he cut back for substitute Luke Gambin, who swung on to his left foot and curled into the bottom right corner.
An incandescent crowd felt N’Gala hauled Andy Williams off his feet in the box in injury-time but Kettle adjudged this to have been a dive on the part of the striker.
Williams would have the last laugh in a see-saw of a game.
Good work from Matty Blair down the right allowed him to a clip a cross into a very dangerous area and Williams was on hand to turn the ball past Vickers and into the near corner.
Barnet sweat blood by the bucket load in the second half, but it was all to no avail for the 198 travelling fans.
