Royal School Dungannon and Belfast High School have it all to do again after a pulsating draw in this third round tie at the Tyrone venue.
Adam White was to score a last gasp try which levelled the match at 17-all.
Loose forward Robbie Reid was handed the task of winning the tie - but it was always going to be a big ask from the touchline.
Dungannon coach Keith Patton said: “I’m delighted with our performance. We’re still in the competition and I think we came of age as a team.”
Belfast High School skipper Tom McConkey said: “We did well to come back and have learnt a lot from this game.
“Hopefully we can get a result at home on Wednesday.”
Dungannon scored 10 points without reply in the first half to deservedly turn around in the lead.
But a spirited fightback by the away team saw them outscore their opponents three tries to one in the second half.
Dungannon never let the High School backs get far and demonstrated pace when out-half John Buckley showed a clean pair of heels to score under the posts after a fine interception. Jack Milligan added the conversion.
The High School’s problems continued as outhalf Joel McBride was sin-binned when the referee adjudged a tip tackle, but scrum-half Milligan missed the penalty attempt.
Around 25 minutes in, Dungannon were unlucky to lose dynamic number eight and captain, Jacob McCammon, with an ankle injury after a strong tackle by his opposite number Scott Shaw.
Dungannon kept the High School under pressure, who gave away too many penalties, one of which was converted by Milligan for the 10-0 interval lead.
Belfast High responded early in the second half with good back play putting Adam White over for the try, converted by flanker Robbie Reid.
But Dungannon quickly restored the 10-point lead when they won a High School lineout. Buckley released centre Matthew Montgomery, who crossed the line after an excellent weaving run.
The visitors replied with a sustained period of possession, but too many passes went to ground. However with 12 minutes to go, the backs finally got a chance to work together when centre Jordan Garford broke away.
Subsequent passes between White, McBride and flanker Connor Elliott released winger Matthew Connolly to score on the right wing, reducing the deficit to five.
However, Dungannon’s excellent tackling kept the High School’s talented three-quarters at bay.
In the last five minutes, with the home side’s forwards keeping BHS camped near their five-metre line, a Royal School win was on the cards.
But after winning a penalty, the away side moved up the pitch with patient, phased rugby, which eventually put White over at the left hand side with the last move of the game. Reid missed the difficult victory conversion attempt.
Royal School Dungannon: Robert McLean; Archie Hanna, Matthew Montgomery, Scott McLean, Stuart Moore; John Buckley, Jack Milligan; Jonathan Black, Jamie McNeill, Charlie Farrell; David Buckley, Calum Bain; David Leyburn, Thomas Downing, Jacob McCammon (c)
Replacements: Tim Brownlow, Andrew Mills, Thomas Fegan, Jonathan Wright, Nathan McCammon, Jonathan Patterson, Josh McKee, Matthew Clarke, Matthew Calvert, Mark Cuddy, Michael Jones
Belfast High School: Jake Hutchinson; Kristian Bell, Jordan Garford, Adam White, Matthew Connolly; Joel McBride, James Creighton; Scott White, Tom McConkey (Capt), Connor McDermott; Lewis Benson, Isaac Edwards; Connor Elliott, Robbie Reid, Scott Shaw
Replacements: Jacob McConkey, Andrew Mitchell, Glenn Brennan, Alan McManus, Jack Steenson, Scott McFarland, Ben Love, Darren Scott