Three stoppage-time goals catapulted Donegal through to the semi-final as Monaghan exited the competition in this high scoring, entertaining contest in Clones on Saturday.
The late goals flattered Donegal. Monaghan started well, with a Niall Garland goal putting them 1-2 to no score ahead after six minutes.
Then Ronan McDermott struck the first of his four goals on 17 minutes and Donegal were level at 1-3.
Monaghan finished the half strongly to lead 1-10 to 1-5 at the break, but Donegal made a rip-roaring start to the second half, hitting 1-6 without reply in 15 minutes. The goal, a second for McDermott, put them in front for the first time.
A point from Kevin Campbell put four between the teams before Monaghan hit their first score of the half 16 minutes from time when Garland raised the green flag again.
With eight minutes left it was deadlocked but a Ciaran Mathewson goal put Donegal ahead on 65 minutes.
Ronan Meegan reduced the deficit to two but as Monaghan pushed forward Donegal hit three late killer goals on the counter through Sean McVeigh and two from McDermott.
Scorers - Donegal: R McDermott 4-0, C Mathewson 1-4 (0-3fs), S McVeigh 1-2, K Campbell 0-4, J Boyle, B Lafferty 0-1 each. Monaghan: R Meegan 0-6 (5fs), N Garland 2-0, S Lambe 0-3, E MacSuibhne, D Crowe, C McKenna, F Rafter 0-1 each.
Donegal- P Burns; J Downey, J Donnelly, M Callaghan; C McDermott, J Boyle, N Cleary; D Cullen, S McVeigh; J O'Loughlin, K Campbell, E McDermott; C Mathewson, R McDermott, B Lafferty. Subs: C Kilgannon for J Downey, S Gillespie for J O'Loughlin.
Monaghan - K Hanniffy; B Flanagan, K Crawley, C McKenna; D Crowe, A Kenny, P Treanor; M Murphy, E MacSuibhne; N Garland, M Treanor, R Meegan; F Rafter, S Lambe, J Guinan. Subs: C Meegan for M Treanor, P Dowdall for E MacSuibhne, T Forde for F Rafter, H Byrne for R Meegan.
Ref - A Nash