Defending Ulster champions Scotstown survived a remarkable Magherafelt comeback to edge a thrilling Ulster Senior Club Football Championship quarter-final 2-21 to 2-20 after extra time in Clones.

Tommy Mallen's goal early in the second period of extra time appeared to have put the Monaghan champions on course for victory, but O'Donovan Rossa produced another extraordinary fightback.

Substitute Caolan Higgins scrambled home a late goal before Conall Higgins struck a two-pointer to leave just one between the sides, but Scotstown held on to book a semi-final meeting with St Eunan's on 22 November.

In regular time, Shane Carney and Cormac Murphy exchanged first-half goals, while a controversial late free awarded against Scotstown goalkeeper Rory Beggan allowed Magherafelt to take the lead in stoppage time before Nicky Sherlock equalised to force extra time.

Magherafelt's Patrick McLarnon opened the scoring before Francis Maguire equalised and Carney finished a flowing Scotstown move involving Jack McCarron and Darragh Murray, firing beyond Odhran Lynch.

Murphy fisted home from close range after Scotstown failed to clear their lines, but the holders responded through Tommy Mallen, Kieran Hughes and McCarron.

The Derry champions recovered to level at 1-6 apiece before two-point efforts from Rory Beggan and Mallen gave Scotstown a 1-10 to 1-6 interval advantage.

Nicky Sherlock stretched that lead to five immediately after the restart, but Magherafelt's relentless pressing helped them register four unanswered points through Shane Heavron, Murphy and McLarnon.

Micheal McCarville and substitute Mattie Maguire steadied Scotstown, although Rory Small's superb long-range two-pointer kept the Derry champions firmly in contention.

Beggan then produced a crucial save to deny Heavron a goal before Murphy's fisted point brought the sides level approaching stoppage time.

There was controversy when Beggan was penalised for a challenge on Heavron, who converted the resulting free to put Magherafelt ahead for the first time since the opening minutes.

However, Sherlock immediately replied to force extra-time at 1-15 apiece.

Scotstown twice established narrow advantages during the opening period of extra-time, but Small and McLarnon responded to leave the sides level again, this time at 1-18 each.

Sherlock edged the holders ahead after the restart before Mallen followed up his own saved effort to fire home Scotstown's second goal.

Further scores from McCarron and Max Maguire appeared to settle the contest, but Magherafelt refused to give up hope.

Caolan Higgins bundled home at the far post before Conall Higgins landed a dramatic two-pointer to reduce the deficit to the minimum.

But Scotstown retained possession in the closing moments to secure a hard-fought victory and keep their Ulster title defence alive.