Ruairi Feeney capped a slick second-half display by St Mary’s to see off Fivemiletown United.
The Irish Cup success marked another positive result under Conor Hagan’s management, with a tactical reshuffle helping wrestle control of the tie.
Fivemiletown took the lead during a strong spell that left St Mary’s on the backfoot.
Feeney finished frustrated by the frame of the goal but St Mary’s next significant effort provided the equaliser.
Feeney and Michael O’Hehir combined to cut open the Fivemiletown backline and Ryan Lawless produced the decisive touch.
The Saints regrouped and sparked a strong second-half display when Feeney moved clear of the offside trip and past the Fivemiletown goalkeeper to score.
The summer signing’s second goal settled the tie as Feeney slotted home Dermot Kelly’s measured pass.
Fivemiletown closed the gap but the Saints survived until the final whistle.