It took 14 minutes for Na Piarsaigh to get on the scoreboard through a point from Aisake Ó hAilpín, as the Rockies led 0-2 to 0-1 after the opening quarter.
At last Na Piarsaigh began to open up the play. Aisake tied the scores with a free and a point from Ronan McGregor put them ahead in the 17th minute.
After Aisake had missed a 25th minute penalty, Setanta's arrival and Sherlock's departure had a huge bearing on the outcome. First Colin O'Sullivan and Setanta scored delightful points, then Setanta ghosted through to set up Christy Connery for a goal that put the winners 1-7 to 0-4 clear at the break.
Blackrock battled on and six minutes into the half Brian O'Keeffe smacked the ball to the net.
Two frees from Coughlan followed and there were just two points between the sides, 1-8 to 1-6, entering the final quarter. Na Piarsaigh switched a rather subdued Seán Óg Ó hAilpín to midfield for the final quarter and immediately they were in for their second goal from Aisake.
With the game opening up and Prendergast lording it at midfield, Na Piarsaigh struck for their third goal in the 54th minute, with Aisake powering through.
Scorers: Na Piarsaigh: A Ó hAilpín 2-3 (0-2 frees), C Connery 1-0, S Ó hAilpín 0-2, R McGregor, C O'Sullivan, S O'Sullivan (10), M Prendergast, S O'Sullivan (12) 0-1 each. Blackrock: A Coughlan 0-5 (0-4 frees, 0-1 '65), B O'Keeffe 1-0, A Browne 0-3 (0-2 frees), B Hennebry, J Young 0-1 each.
NA PIARSAIGH: M O'Sullivan; D Murphy, R O'Byrne, D Mannix; J Gardiner, D Gardiner, S Óg Ó hAilpín; M Prendergast, R McGregor; C O'Sullivan, C Connery, C O'Mahony; A Ó hAilpín, Steve O'Sullivan, Stephen O'Sullivan. Subs: S Ó hAilpín for O'Mahony, G Shaw for S O'Sullivan (13), D Walsh for Connery.
BLACKROCK: T Barry; C Murphy, W Sherlock, J Browne; A Ryan, F Ryan, P McGrath; A Coughlan, P Tierney; J Young, L Meaney, B Hennebry; B O'Keeffe, A Browne, D Cashman. Subs: S Murphy for Sherlock, D Gosnell for Cashman, TJ Coughlan for A Browne.
Referee: C McAllister (Midleton).