Two first-half goals paved the way for St Mochta's victory over highly-fancied Ulster Senior League side, Swilly Rovers.
The Leinster senior league side got off to a dream start, scoring their first goal inside three minutes. Striker David Cummins collected a quick free from central defender Donal Massey to crack home a super goal from 25 metres.
Ten minutes later, the Dublin side were two up. This time Kieran Fitzpatrick from a similar distance sent in a cross which went straight in.
Playing with the assistance of a gale-force wind, the visitors could easily have been five up by the 30 minute mark. Twice Swilly keeper, Jim Harley, denied man of the match, Cummins, while the keeper finger-tipped a Gareth Groves's 20-yard drive over for a corner.
Getting to grips with the twin threat of Fitzpatrick and Cummins, Swilly came more into the game as the half wore on.
Martin Doherty got on the end of a good move only to see his delicate flick squirm wide of the upright. Swilly had a goal ruled out just on the stroke of halftime, Gary Heaney judged offside.
Within three minutes of the restart, the home side were back in the contest, Heaney volleying a Steven Donaghy cross to the back of the St Mochta's net. However, despite the early goal, Swilly could not break down a well-drilled St Mochta's defence.
And while the visitors lived dangerously for the remainder of the match, they held on for a fully deserved and famous victory and a place in the last eight of the competition.
Recent signing Gordon Johnson scored his first goal for Monaghan United to salvage a point against St Francis at Gortakeegan yesterday and extend their unbeaten run to four games and lift them to sixth in the table.
Johnson met a James O'Callaghan corner on 76 minutes to power a header past Cathal Warfield in the St Francis goal.
Gavin Doyle had scored his seventh goal of the season to give St Francis an 18th minute lead from a penalty after Nicholas McCarville had fouled Stuart keegan inside the area.
Swilly Rovers: Harley, Colhoun, Rogers, McDaid, Gallagher, Gildea, Sheridan, Lafferty, Doherty, Heaney, Porter. Subs: Donaghy for Colhoun (49 mins), McHugh for Sheridan (81 mins), Patten for Rogers (91 mins).
St Mochta's: Quane, Keating, Salmon, Kelly, Balfe, Massey, Groves, Norton, Fitzpatrick, Donovan, Cummins. Subs: Hughes for Groves (half-time), Seery for Donovan (84 mins).
Referee: S Devenney, Donegal.