The win was fashioned around a second-half try by second Cian Bohane that had the hallmark of sheer brilliance and came in a rare second-half incursion into the Crescent half of the field as Pres spent most of the 35 minutes entrenched between their own 25 and the half way line.
To make it all the sweeter Crescent were on the offensive when the Pres fly-half, Kevin Kidney, emerged from the back of the ruck, dummied Crescent to the left and then passed the ball to the right and into the welcoming hands of hands of Bohane who launched his lone crusade.
Nobody could match strides with the fleet-footed second centre although Crescent winger, Jurgen Quinlan, was closing him down all the way to the line. But when he eventually got the tackle in it was too late to prevent Bohane touching down.
Kidney, whose pass lifted the siege, made no mistake with the conversion, and while Johnny McCarthy would get over in the corner for a second Pres try deep into injury time this was the score that would decide the semi-final place.
Two weeks earlier PBC took Ard Scoil Rís for a romp in the park but it was evident from an early stage that the extravagances of that game were not going to be repeated against a well organised Crescent side.
Pres got their first points from the boot of Kevin Kidney who kicked a long range penalty three minutes into the game and, after Ben Sargent missed the opportunity to equalise, this was the score that would separate the sides at the interval.
There were ominous signs, however, with Pres relying on Bryan Carroll in the line-out against Gavin Fleming, Padraig Monaghan and Paul Canty on the other side.
And when Crescent came out full of running in the second-half the Cork side was on the back foot and they were under siege until the Bohane try in the 10th minute.
The Pres defence showed remarkable discipline under the incessant pressure and when they eventually conceded a penalty in front of the posts Ben Sargent missed the target.
Crescent were resigned to their fate when Will Murphy blocked the ball down and Pres got it out across the line to Johnny McCarthy who crashed over in the corner for their second try two minutes into injury-time.
PBC, who ran in nine tries against Ard Scoil Rís, have their defence to thank for this win. While Patrick O’Connell and Jack Costigan got in some good tackles it was the grinding performances from Niall Scannell, Brian Vaughan and Ian Mullarkey in the engine room, combined with disciplined defending by Conail Murphy, Jack Duffy and Bryan Carroll that won the day.
PRESENTATION BROTHERS COLLEGE: J. Costigan; P O’Connell, C. Bohane, J. McCarthy, W. Murphy; K. Kidney, R. Barry; N. Scannell, B. Vaughan, I. Mullarkey; R. O’Herlihy, D. O’Mahony, C. Murphy, J. Duffy, B. Carroll.
Replacement: J. O’Sullivan for R. O’Herlihy (58 mins).
CRESCENT COLLEGE: T. Ryan; J. Quinlan, J. J. O’Toole, B. Sargent, D. O’Doherty; G. Quin-McDonagh, A. Healy; J. Randles, C. O’Connor, J. Flannery; G. Fleming, P. Monaghan; J. Randles, C. O’Connor, J. Flannery.
Replacements: C. Russell for P. Canty, S. Upton for A. Healy, E. Cross for I. Sherlock (44 mins), L. Darcy for J. Randles (65 mins).
Referee: B. O’Connell (Munster Branch).