The hosts lit up a dank Kingspan/Breffni Park in the first half to go 0-10 to 0-3 ahead but Sligo were a transformed outfit after the break, hitting an unanswered 1-4, and came within inches of sneaking a draw.
Cavan Gaels speedsters Niall Smith, Kevin Meehan and Martin Dunne were a revelation, making little of the absence of their club colleague Sean Johnston during a brilliant first half.
The lead was extended to nine points, 0-12 to 0-3, after 41 minutes before Sligo hit a purple patch when three points by Adrian Marren sandwiched a Colm McGee goal (49).
However, a classy Martin Dunne point stopped the rot for Cavan and when Sligo’s Brendan Egan was sent off for a second yellow card it seemed like Cavan would coast home.
Yet the westerners dominated the final 15 minutes and were desperately unlucky not to snatch a draw as sub David Kelly’s close-range effort on goal was brilliantly blocked by Damien Reilly.
Scorers for Cavan: M Dunne 0-4 (2f), G McKiernan 0-3, K Meehan (1f), B Fitzpatrick 0-2 each, R Maloney-Derham, D Givney, N Smith 0-1 each.
Scorers for Sligo: A Marren 0-5 (2f), C McGee 1-2 (1 45), M Breheny 0-1.
CAVAN: J Reilly; D Barkey, D Reilly, R Flanagan; B Watters, P O’Reilly, R Maloney-Derham; D Givney, G McKiernan; N Smith, M McKeever, K Meehan; N McDermott, E Keating, M Dunne.
Subs: B Fitzpatrick for E Keating (inj, 3); N Murray for K Meehan (60); D McKiernan for B Watters (65); D O’Dowd for N McDermott (65); S Jordan for N Smith (69).
SLIGO: P Greene; C Harrison, B Kennedy, R Donovan; J Davey, S McManus, P McGovern; E Mullen, B Egan; M Breheny, A Costello, P Hughes; C McGee, J Clarke, A Marren.
Subs: T Taylor for E Mullen (inj, 12); J Martyn for B Kennedy (inj, 27); D Rooney for P McGovern (34) M Quinn for J Davey (43); D Kelly for M Breheny (47).
Referee: P Fox (Westmeath).