Ciaran Corrigan was the Fermanagh hero as his 73rd minute point gave the gritty comeback kids from the Erne one of their greatest ever victories in Brewster Park.
It was a fitting reward for the versatile wing forward who was excellent throughout.
The home side were trailing by 0-12 to 0-11 with ordinary time up after Roscommon led them by 0-9 to 0-3 at the break.
But a rousing second half display from the majestic Conall Jones brought his team mates back into contention after they went behind by 0-5 to 0-0 after just 19 minutes.
Jones struck four superb points as the Ernesider recovered from a 0-9 to 0-3 defecit where they were totally outplayed by the Connacht champions for whom Niall Kilroy was very impressive.
And a vastly improved midfield display from Eoin Donnelly and Ryan Jones was the platform for this deserved victory.
But Roscommon team boss Anthony Cunningham will be disappointed that his men could only manage a total of three points in 39 minutes of play.
Roscommon shipped an early blow when they lost midfielder Shane Killoran who was stretchered off with a serious looking leg injury.
But they recovered splendidly to totally dominate their listless opponents for the rest of the half.
Lively full-forward Cian McKeon opened their account from a pointed free after six minutes.
Roscommon looked far livelier and McKeon added another from a free as Fermanagh put 15 men behind the ball.
Substitute Donie Smith added to their tally and impressive full back Brian Stack and elegant wing forward Niall Kilroy made it a 0-5 to 0-0 lead by the 19th minute.
Fermanagh eventually awoke and towering midfielder Donnelly strode through for a superb point.
This was quickly added to with similar efforts from wing forwards Aidan Breen and Ciaran Corrigan to leave just two points between the sides by the 25th minute.
They also had a half chance of a goal in the 26th minute but Rossies keeper Colm Lavin denied Conal Jones and Stephen McGullion goal bound efforts.
But the final ten minutes belonged to the much livelier Rossies who stretched their lead with further scores from Kilroy, Smith and McKeon to leave the Connacht men deservedly leading by 0-9 to 0-3 at the break.
Fermanagh were first out after the break as a rainbow stole over Brewster Park.
Conall Jones gave them some inspiration with a point from a free and a wonderful effort from the side line to narrow the gap to 0-9 to 0-5 as the sun replaced the niggling rain .
But the lanky Hubert D'arcy responded with a soaring effort from the wing to extend the lead to 0-10 to 0-5
The beavering Ciaran Corrigan got his second for Fermanagh after good work on the wing in the 48th minute.
Corrigan won another free and Jones made it 0-10 to 0-7 from the resultant placed ball as the rate of scoring intensified.
Jones was on target again from a free in the 50th minute as the Ernesiders began to win their individual battles and suddenly there was just two points in the match.
It was real helter-skelter stuff for the last quarter with the Ernesides whittling the Rossies lead down to set up a truly frenetic finish.
Fermanagh: J McGrath; J Cassidy, C Cullen, K McDonnell; E Sheils, R O’Callaghan, Shane McGullion; E Donnelly (0-1), R Jones (0-1); A Breen (0-1) U Kelm (0-1) C Corrigan (0-3); Stephen McGullion, C Jones (0-63f) L McStravick.
Subs: D McCusker for L McStravick (41), D Teague for Shane McGullion (55), N Cosgrove for E Shiels (66), E McManus for A Breen (68)
Roscommon: C Lavin; D Murray, C Daly (0-1) G Patterson; N Daly, B Stack (0-1) E McGrath (0-1); ;T O’Rourke, S Killoran; N Kilroy (0-2) E Smith; C Lennon; H Darcy (0-1) C McKeon (0-4f), C Cregg.
Subs: D Smith (0-1) for S Killoran (inj 2), R Hughes for T O’Rourke (57) F Cregg (0-1) for C Cregg( 59), D Ruane for H D’arcy (61)
Referee: C Reilly (Meath)