Crescent's dream of a third title in four years is alive and well after a hard-fought win in Rosbrien.
A try out of the top drawer from Anson Thai and a powerful centre partnership proved key to Crescent's victory, and the margin could have been more but for a number of missed kicks at goal.
Underdogs Glenstal went ahead through a Jack Stafford penalty, but Crescent levelled with a penalty from Cian Clifford before Peter Hickey's try put them ahead.
Loosehead Thai was dominating the scrum, and showed superb step and speed to score his side's second unconverted try.
Crescent were 13-3 up at half-time, and a Clifford penalty soon extended the lead to 13. However, when Niall Mulcahy was sin-binned after 53 minutes, Glenstal smelled blood, and reduced the gap when George O'Hara touched down.
Calvin Nash steadied the Crescent ship with three monstrous tackles, and his centre partner Billy O'Hora then sealed the win with a try as injury-time approached, Clifford converting.
Colm Hogan's try gave Glenstal a glimmer of hope, but Crescent comfortably held out to book a home semi-final with either Rockwell or CBC.
Crescent College – G Dickinson; C McSweeney, B O'Hora, C Nash, J Young O'Connor; C Clifford, J Lyons; A Thai, J Barry, S Scanlon Garry (S Downes 58); B Considine, J Blake (K Murphy 60); C Slattery, P Hickey, N Mulcahy.
Glenstal Abbey – C Gavin; S O'Sullivan (K Glynn 40), T Costigan, C Hogan, G Daly; J Stafford, R Johnston; L Lynch, J Williams, D Quane; T Broderick (R Clarke 60), A Donohue; W Murphy, J Enright, G O'Hara.
Ref – A Brace